Update Charmhub home page (14)

[a-velasco]

This PR updates the metadata.yaml for PostgreSQL 14 releases on Charmhub in order to version the home page with the docs.

It addresses issue canonical/postgresql-operator#1082

Changes

• Replaced docs: link with new RTD docs - this new Charmhub feature will create a dedicated button in the sidebar.
• Updated summary: and description: keys, since they will be the new title and content of the Charmhub home page.
• Removed old broken link to chat.charmhub.io

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.29%. Comparing base (655b251) to head (b803a40).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1069   +/-   ##
=======================================
  Coverage   73.29%   73.29%           
=======================================
  Files          15       15           
  Lines        3921     3921           
  Branches      574      574           
=======================================
  Hits         2874     2874           
  Misses        833      833           
  Partials      214      214           

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