Updates the tutorial for writing help center articles to encourage
contributors to add to or enhance the existing help center docs
before writing a new articles for new features.
Also, generally updates references to 'user documentation' to be
'help center documentation'.
Additionally, updates some headers within the tutorials for clarity
and consistency, and adds some linkifying throughout the section on
writing documentation.
This commit helps reduce clutter on the navigation sidebar.
Creates new directories and moves relevant files into them.
Modifies index.rst, symlinks, and image paths accordingly.
This commit also enables expandable/collapsible navigation items,
renames files in docs/development and docs/production,
modifies /tools/test-documentation so that it overrides a theme setting,
Also updates links to other docs, file paths in the codebase that point
to developer documents, and files that should be excluded from lint tests.
Note that this commit does not update direct links to
zulip.readthedocs.io in the codebase; those will be resolved in an
upcoming follow-up commit (it'll be easier to verify all the links
once this is merged and ReadTheDocs is updated).
Fixes#5265.
Anders Kaseorg
Lauryn Menard
Tim Abbott
Anders Kaseorg
Stefan Weil
David Rosa Tamsen