Update CHANGELOG for 8.3.0

[martincostello]

Add changelog entries for the 8.3.0 release.

[martincostello]

Have also added this to the draft GitHub release:

[peter-csala]

I think we should delete the This documentation page describes an upcoming feature of Polly. warnings from the documentation pages.

[martincostello]

Good catch! I'll push up a commit to remove that...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e937886) 85.91% compared to head (50a2584) 85.91%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1954   +/-   ##
=======================================
  Coverage   85.91%   85.91%           
=======================================
  Files         312      312           
  Lines        6654     6654           
  Branches     1057     1057           
=======================================
  Hits         5717     5717           
  Misses        540      540           
  Partials      397      397           

Flag	Coverage Δ
linux	85.91% <ø> (ø)
macos	85.91% <ø> (ø)
windows	?

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.