docs: onboard perf configs guide

[sandeepvinayak]

Summary

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Some conventions to follow

1. add the module name as a prefix
   • for example: add a prefix: docstore: for document store module, blobstore for Blob Store module
2. for a test only PR, add test:
3. for a perf improvement only PR, add perf:
4. for a refactoring only PR, add "refactor:"