[release] Add release notes link on stable releases

[CodeBlanch]

Relates to #5772

Changes

• Add a link to new RELEASENOTES.md file on GitHub releases when releasing a stable version
• Add a link to the previous release on all GitHub releases to help users find everything which changed across releases

Test runs

• https://github.com/CodeBlanchOrg/opentelemetry-dotnet/releases/tag/core-1.10.0-alpha.1
• https://github.com/CodeBlanchOrg/opentelemetry-dotnet/releases/tag/core-1.10.0

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.20%. Comparing base (6250307) to head (3fee7f4).
Report is 289 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5780      +/-   ##
==========================================
+ Coverage   83.38%   86.20%   +2.81%     
==========================================
  Files         297      256      -41     
  Lines       12531    11140    -1391     
==========================================
- Hits        10449     9603     -846     
+ Misses       2082     1537     -545     

Flag	Coverage Δ
unittests	?
unittests-Project-Experimental	85.87% <ø> (?)
unittests-Project-Stable	85.83% <ø> (?)
unittests-Solution	86.18% <ø> (?)
unittests-UnstableCoreLibraries-Experimental	85.79% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

see 203 files with indirect coverage changes

[vishweshbankwar]

LGTM