docs: Rename postgres.md to postgresql.md.

docs/_templates/layout.html

@@ -5,7 +5,7 @@
     # version e.g. to say that something is likely to have changed.
     # For more info see: https://www.sphinx-doc.org/en/master/templating.html
     #}
-    {% if pagename in ["production/video-calls"] and release.endswith('+git') %}
+    {% if pagename in ["production/postgresql", "production/video-calls"] and release.endswith('+git') %}
     {#
     # This page doesn't exist in the stable documentation yet.
     # This temporary workaround prevents CircleCI failure and should be removed after the next release.

docs/production/index.rst

@@ -15,7 +15,7 @@ Zulip in production
    security-model
    authentication-methods
    export-and-import
-   postgres
+   postgresql
    upload-backends
    ssl-certificates
    email

docs/production/requirements.md

@@ -150,7 +150,7 @@ installing Zulip with a dedicated database server.
 
 * **Dedicated database**.  For installations with hundreds of daily
   active users, we recommend using a [remote PostgreSQL
-  database](postgres.md), but it's not required.
+  database](postgresql.md), but it's not required.
 
 * **RAM:**  We recommended more RAM for larger installations:
     * With 25+ daily active users, 4GB of RAM.