Document Prometheus metrics and OLAP Flow events

[hasit]

Description of change

Closes: #720

Checklist

• Tested in playground or other setup
• Documentation is changed or added
• Tests and/or benchmarks are included
• Breaking changes

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This change is 

[codecov]

Codecov Report

Base: 37.57% // Head: 37.53% // Decreases project coverage by -0.03% ⚠️

Coverage data is based on head (862eb1a) compared to base (a642494).
Patch has no changes to coverable lines.

❗ Current head 862eb1a differs from pull request most recent head 85f1a87. Consider uploading reports for the commit 85f1a87 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #878      +/-   ##
==========================================
- Coverage   37.57%   37.53%   -0.04%     
==========================================
  Files         279      279              
  Lines       20592    20592              
==========================================
- Hits         7737     7729       -8     
- Misses      12378    12384       +6     
- Partials      477      479       +2     

Impacted Files	Coverage Δ
pkg/otelcollector/metricsprocessor/processor.go	63.24% <ø> (ø)
pkg/otelcollector/rollupprocessor/processor.go	87.15% <ø> (ø)
...ol/actuators/concurrency/scheduler/token-bucket.go	91.48% <0.00%> (-4.26%)	⬇️
...flowcontrol/actuators/concurrency/scheduler/wfq.go	93.79% <0.00%> (-1.31%)	⬇️

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