docs: comprehensive log collector documentation

RCA: perf-regression-predefined-throughput-steps-i8g-tablets failure (Apr 26) — transient read admission queue saturation

5 minutes not enough for parallel cleanup after added new node

Scyllabench failed to run with counter mode: `Unknown scylla-bench mode: ScyllaBenchModes.COUNTER_UPDATE`

extend "topology change coordinator fiber got error std::runtime_error" for disrupt_terminate_and_replace_node nemesis

Make Group0 membership read strict and retry only expected CQL exceptions

[artifacts] failing during `Collect log data()` stage

disrupt_delete_by_rows_range failed with: "Exception: No partitions for deletion found. Cannot execute a range deletion."

The SCT log is not being saved periodically. Error: `AttributeError: 'dict' object has no attribute 'subcontext_fields'`

disrupt_no_corrupt_repair finished with "Exit code: 1" due to "Can't find a column family standard1 in keyspace drop_table_during_repair_ks_0"