Document ruff_dev and format_dev (#5648)

## Summary

Document all `ruff_dev` subcommands and document the `format_dev` flags
in the formatter readme.

CC @zanieb please flag everything that isn't clear or missing

## Test Plan

n/a

crates/ruff_dev/src/generate_all.rs

@@ -21,7 +21,7 @@ pub(crate) enum Mode {
     /// Don't write to the file, check if the file is up-to-date and error if not.
     Check,
 
-    /// Write the generated help to stdout (rather than to `docs/configuration.md`).
+    /// Write the generated help to stdout.
     DryRun,
 }
 

crates/ruff_dev/src/generate_options.rs

@@ -1,4 +1,6 @@
-//! Generate a Markdown-compatible listing of configuration options.
+//! Generate a Markdown-compatible listing of configuration options for `pyproject.toml`.
+//!
+//! Used for <https://beta.ruff.rs/docs/settings/>.
 use itertools::Itertools;
 
 use ruff::settings::options::Options;

crates/ruff_dev/src/generate_rules_table.rs

@@ -1,4 +1,6 @@
 //! Generate a Markdown-compatible table of supported lint rules.
+//!
+//! Used for <https://beta.ruff.rs/docs/rules/>.
 
 use itertools::Itertools;
 use strum::IntoEnumIterator;