Update changelog with PostgreSQL Source Connector GA

[VineethReddy02]

Added details about the PostgreSQL Source Connector reaching GA status, including new features and improvements.

Describe your changes

What did you change? Why did you change it?

Related Issues

If there is a related issue, please add it below (just put the number after the # below, and GitHub will automatically create a link):

Issue: #number

Checklist before requesting a review

• - Is this ready for review? If not, raise as a draft PR
• - This has deployed to a staging environment correctly
• - I have reviewed my changes.
• - I have confirmed the content is technically accurate.
• - I have confirmed the content is free of typos or grammar errors.
• - I have reviewed the deployed version of my changes.
• - I have tested any code that is added or updated.
• - I have verified all images and videos are clear, with appropriate zoom.
• - I have verified all images and videos match production (or dev for unreleased features).
• - I have tested that the content matches the functionality in production (or dev for unreleased features).
• - All checks have passed.
• - This references a feature that is public. If not, add a note and we can schedule the merge for after the feature release.

[github-actions]

Allow 10 minutes from last push for the staging site to build. If the link doesn't work, try using incognito mode instead. For internal reviewers, check web-documentation repo actions for staging build status. Link to build for this PR: http://docs-dev.timescale.com/docs-update-changelog-with-pg-ga