More documentation and API changes

[Boshen]

I'm clicking around and listing all the missing documentation and confusing APIs for me to work on:

• [x] crate README https://crates.io/crates/oxc
• [x] crate level https://docs.rs/oxc/0.30.1/oxc
• [ ] import SourceType from oxc_span?
• [ ] So many options in https://docs.rs/oxc_transformer/0.30.1/oxc_transformer/index.html, where's the entry point?
• [ ] Tranformer: super confusing entry point targets vs Options
• [x] Many unintended pub in all of the crates
• [x] https://www.npmjs.com/package/oxc-transform Usage example is outdated.
• [ ] npm packages should list binary files with their rough binary size for connivence.
• [ ] If an API has performance impact, it should be documented with % change.
• [ ] https://www.npmjs.com/package/oxc-parser should mention we don't have d.ts yet (or figure out how to get it from the wasm version).
• [ ] Align the shape of all APIs for npm packages (parser and transformer)
• [x] consolidate benchmark results on oxc.rs https://oxc.rs/docs/guide/benchmarks.html
• [x] update https://oxc.rs/docs/guide/usage/transformer.html
• [ ] Eliminate confusing terms by building a glossary?
• [x] document https://crates.io/crates/oxc_module_lexer

EDIT (@DonIsaac): related: #5870

[DonIsaac]

I'm clicking around and listing all the missing documentation and confusing APIs for me to work on:

• [ ] crate README https://crates.io/crates/oxc
• [ ] crate level https://docs.rs/oxc/0.30.1/oxc

Added in #6035

[DonIsaac]

• [ ] Eliminate confusing terms by building a glossary?

We have one, though it's not very detailed and out of date.

[Boshen]

I updated most of the outdated ones.