[docs] Outline easy optimizations for endpoints

[emostov]

There should be some documentation on what query params for specific endpoints can improve performance.

This would likely outline the options for specific paths that reduce RPC calls, computation, etc.

I think there can be notes added to query params in the docs mentioning what might be faster and also quick "Optimization getting started" guide in the README that points out some common use cases. For example, the most obvious things to me are opting out of the authorId in the blocks endpoint or opting out of the metadata in the transaction material endpoint unless there has been a runtime upgrade.