docs: Reorganize sections and pages about contributing to Zulip.

We should rearrange Zulip's developer docs to make it easier to
find the documentation that new contributors need.

Name changes
Rename "Code contribution guide" section -> "Contributing to Zulip".
Rename "Contributing to Zulip" page -> "Contributing guide".

Organizational changes to the newly-named "Contributing to Zulip":
Move up "Contributing to Zulip", as the third link in sidebar index.
Move up renamed "Contributing guide" page to the top of this section.
Move up "Zulip code of Conduct", as the second link of this section.
Move down "Licensing", as the last link of this section.
Move "Accessibility" just below "HTML and CSS" in Subsystems section.

Update all links according to the changes above.
Redirects should be added as needed.

Fixes: #22517.

CONTRIBUTING.md

@@ -1,4 +1,4 @@
-# Contributing to Zulip
+# Contributing guide
 
 Welcome to the Zulip community!
 
@@ -184,7 +184,7 @@ stream](https://chat.zulip.org/#narrow/stream/101-design) in the [Zulip
 development community](https://zulip.com/development-community/)
 
 For more advice, see [What makes a great Zulip
-contributor?](https://zulip.readthedocs.io/en/latest/overview/contributing.html#what-makes-a-great-zulip-contributor)
+contributor?](#what-makes-a-great-zulip-contributor)
 below.
 
 ### Submitting a pull request
@@ -267,7 +267,7 @@ The key to keeping your review moving through the review process is to:
 - Make it as easy as possible to review the changes you made.
 
 In order to do this, when you believe you have addressed the previous round of
-feedback on your PR as best you can, post an comment asking reviewers to take
+feedback on your PR as best you can, post a comment asking reviewers to take
 another look. Your comment should make it easy to understand what has been done
 and what remains by:
 
@@ -314,7 +314,7 @@ labels.
      on [Git commit
      discipline](https://zulip.readthedocs.io/en/latest/contributing/version-control.html#commit-discipline).
   2. If all the feedback has been addressed, did you [leave a
-     comment](https://zulip.readthedocs.io/en/latest/overview/contributing.html#how-to-help-move-the-review-process-forward)
+     comment](#how-to-help-move-the-review-process-forward)
      explaining that you have done so and **requesting another review**? If not,
      it may not be clear to project maintainers or reviewers that your PR is
      ready for another look.

docs/contributing/gsoc.md

@@ -67,7 +67,7 @@ also give you a feel for what it's like to do GSoC with us.
 
 We have an easy-to-set-up development environment, and a library of
 tasks that are great for first-time contributors. Use
-[our first-time Zulip developer guide](../overview/contributing.md#your-first-codebase-contribution)
+[our first-time Zulip developer guide](contributing.md#your-first-codebase-contribution)
 to get your Zulip development environment set up and to find your first issue. If you have any
 trouble, please speak up in the
 [#GSoC](https://chat.zulip.org/#narrow/stream/14-GSoC) stream on the
@@ -135,7 +135,7 @@ For the first time in 2022, being a student is not required in order to apply to
 GSoC. We are happy to accept both student and non-student participants.
 
 Our documentation on [what makes a great Zulip
-contributor](../overview/contributing.md#what-makes-a-great-zulip-contributor)
+contributor](contributing.md#what-makes-a-great-zulip-contributor)
 offers some additional helpful information. We also recommend reviewing the
 [official GSoC
 resources](https://developers.google.com/open-source/gsoc/resources/),
@@ -169,7 +169,7 @@ other contributors learn from reading the conversation.
   - [Try, Then Ask](https://www.mattringel.com/2013/09/30/you-must-try-and-then-you-must-ask/)
   - [We Aren’t Just Making Code, We’re Making History](https://www.harihareswara.net/sumana/2016/10/12/0)
   - [How to Ask Good Questions](https://jvns.ca/blog/good-questions/)
-- Understand [what makes a great Zulip contributor](../overview/contributing.md#what-makes-a-great-zulip-contributor)
+- Understand [what makes a great Zulip contributor](contributing.md#what-makes-a-great-zulip-contributor)
 
 This is a typical question/response sequence:
 

docs/contributing/index.md

@@ -1,18 +1,18 @@
-# Code contribution guide
+# Contributing to Zulip
 
 ```{toctree}
 ---
 maxdepth: 3
 ---
 
+contributing
+../code-of-conduct
 version-control
 code-style
 code-reviewing
 zulipbot-usage
-accessibility
-licensing
 bug-reports
-../code-of-conduct
 gsoc
 summer-with-zulip
+licensing
 ```

docs/index.md

@@ -8,7 +8,7 @@ Welcome! Zulip's documentation is split into four parts:
   installing and maintaining a production self-hosted Zulip installation.
 - [API documentation](https://zulip.com/api/), for writing
   integrations or bots using the Zulip API.
-- [Contributor documentation](overview/contributing.md), for
+- [Contributor documentation](contributing/contributing.md), for
   developing the Zulip software, translating, submitting bug reports,
   or making other contributions to the project.
 
@@ -20,17 +20,16 @@ the Zulip project and its features can be found at
 
 This site contains our installation and contributor documentation. If
 this is your first time here, you may want to start with [Production
-installation](production/install.md) or [Contributing to
-Zulip](overview/contributing.md).
+installation](production/install.md) or [Contributing guide](contributing/contributing.md).
 
 Contents:
 
 - {ref}`Overview <overview>`
 - {ref}`Zulip in production <zulip-in-production>`
+- {ref}`Contributing to Zulip <contributing-to-zulip>`
 - {ref}`Development environment <development-environment>`
 - {ref}`Developer tutorials <developer-tutorials>`
 - {ref}`Git guide <git-guide>`
-- {ref}`Code contribution guide <code-contribution-guide>`
 - {ref}`Code testing <code-testing>`
 - {ref}`Subsystem documentation <subsystem-documentation>`
 - {ref}`Writing documentation <writing-documentation>`
@@ -56,6 +55,16 @@ maxdepth: 3
 production/index
 ```
 
+(contributing-to-zulip)=
+
+```{toctree}
+---
+maxdepth: 3
+---
+
+contributing/index
+```
+
 (development-environment)=
 
 ```{toctree}
@@ -86,16 +95,6 @@ maxdepth: 3
 git/index
 ```
 
-(code-contribution-guide)=
-
-```{toctree}
----
-maxdepth: 3
----
-
-contributing/index
-```
-
 (code-testing)=
 
 ```{toctree}

docs/overview/index.md

@@ -6,7 +6,6 @@ maxdepth: 3
 ---
 
 readme
-contributing
 architecture-overview
 directory-structure
 release-lifecycle

docs/overview/release-lifecycle.md

@@ -184,7 +184,7 @@ GitHub issue. Please an include an explanation of your use case: such
 details can be extremely helpful in designing appropriately general
 solutions, and also helps us identify cases where an existing solution
 can solve your problem. See [Reporting
-issues](contributing.md#reporting-issues) for more details.
+issues](../contributing/contributing.md#reporting-issues) for more details.
 
 ## Client apps
 

docs/production/upgrade-or-modify.md

@@ -822,7 +822,7 @@ upgrading to `main`, make sure you understand:
 Zulip contains thousands of changes submitted by volunteer
 contributors like you. If your changes are likely to be of useful to
 other organizations, consider [contributing
-them](../overview/contributing.md).
+them](../contributing/contributing.md).
 
 [fork-clone]: ../git/cloning.md#get-zulip-code
 [upgrade-zulip-from-git]: #upgrading-from-a-git-repository

docs/subsystems/index.md

@@ -8,6 +8,7 @@ maxdepth: 3
 dependencies
 settings
 html-css
+accessibility
 events-system
 sending-messages
 notifications

templates/zerver/help/high-contrast-mode.md

@@ -11,4 +11,4 @@ W3C's Web Content Accessibility Guidelines.
 
 ## Related articles
 
-* [Accessibility in Zulip](https://zulip.readthedocs.io/en/latest/contributing/accessibility.html)
+* [Accessibility in Zulip](https://zulip.readthedocs.io/en/latest/subsystems/accessibility.html)

tools/linter_lib/custom_check.py

@@ -847,7 +847,7 @@ markdown_rules = RuleList(
         {
             "pattern": "https://zulip.readthedocs.io/en/latest/[a-zA-Z0-9]",
             "exclude": {
-                "docs/overview/contributing.md",
+                "docs/contributing/contributing.md",
                 "docs/overview/readme.md",
                 "docs/README.md",
                 "docs/subsystems/email.md",