docs: explain how to decrease JWT length in Keycloak

[aler9]

this prevents errors when passing JWT with FFmpeg and GStreamer.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52.74%. Comparing base (7b02c28) to head (706fe2a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5012      +/-   ##
==========================================
- Coverage   52.75%   52.74%   -0.02%     
==========================================
  Files         163      163              
  Lines       18870    18870              
==========================================
- Hits         9955     9953       -2     
- Misses       8209     8211       +2     
  Partials      706      706              

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[github-actions]

This issue is mentioned in release v1.15.1 🚀
Check out the entire changelog by clicking here