Update CHANGELOG and README for 2.2.0

[ciarams87]

Proposed changes

Problem: The CHANGELOG and README need to be updated after the 2.2.0 release

Solution: Update the files

Testing: Describe any testing that you did.

Please focus on (optional): If you any specific areas where you would like reviewers to focus their attention or provide
specific feedback, add them here.

Closes #ISSUE

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.51%. Comparing base (c775781) to head (3d94866).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4138   +/-   ##
=======================================
  Coverage   86.51%   86.51%           
=======================================
  Files         131      131           
  Lines       17796    17796           
  Branches       74       74           
=======================================
  Hits        15397    15397           
  Misses       2199     2199           
  Partials      200      200           

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[bjee19]

WIll you update the chart files like we did here https://github.com/nginx/nginx-gateway-fabric/pull/3741/files#diff-10e9cedc83a7db11ba650cb1f5f3fe511735545a8425aca8c0f4be7906a1cb5f?