Create development documentation for usage of `mem_*` usage logs
Proposal
Follow-up after #296530 (closed).
With the work on #296530 (closed) we merged a set of additional metrics:
- mem_objects
- mem_bytes
- mem_mallocs
We should update development documentation to describe their meaning and usage.
Dependencies
This requires feature flag to be rolled out: #299524 (closed)
Edited by Kamil Trzciński