docs(prestate): comment prestate more clear

[jsvisa]

Motivation

1. fix an clippy warning:

warning: first doc comment paragraph is too long
  --> crates/provider/src/layers/cache.rs:61:1
   |
61 | / /// The [`CacheProvider`] holds the underlying in-memory LRU cache and overrides methods from the
62 | | /// [`Provider`] trait that should attempt to fetch from cache and fallback to the RPC in case of a
63 | | /// cache miss.
64 | | ///
65 | | /// Most importantly, the [`CacheProvider`] adds `save_cache` and `load_cache` methods to the
   | |_
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_long_first_doc_paragraph
   = note: `-W clippy::too-long-first-doc-paragraph` implied by `-W clippy::all`
   = help: to override `-W clippy::all` add `#[allow(clippy::too_long_first_doc_paragraph)]`

warning: `alloy-provider` (lib) generated 1 warning

2. make the prestate comments more clear

Solution

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes