docs: Replace the old events calendar by the OpenFeature community Page link

[oleg-nenashev]

https://openfeature.dev/community/ is a better source of truth

This PR

• adds this new feature

Related Issues

Fixes #1234523

Notes

Follow-up Tasks

How to test

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.77%. Comparing base (499661e) to head (c585573).
Report is 57 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #751       +/-   ##
===========================================
- Coverage   86.51%   71.77%   -14.74%     
===========================================
  Files          19       30       +11     
  Lines        1587     2289      +702     
===========================================
+ Hits         1373     1643      +270     
- Misses        173      598      +425     
- Partials       41       48        +7     

see 11 files with indirect coverage changes

Flag	Coverage Δ
unit-tests	71.77% <ø> (-14.74%)	⬇️

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[beeme1mr]

Thanks!