docs(transformer): add documentation for optional-catch-binding plugin

crates/oxc_transformer/src/es2019/optional_catch_binding.rs

@@ -1,3 +1,37 @@
+//! ES2019: Optional Catch Binding
+//!
+//! This plugin transform catch clause without parameter to add a parameter called `unused` in catch clause.
+//!
+//! > This plugin is included in `preset-env`, in ES2019
+//!
+//! ## Example
+//!
+//! Input:
+//! ```js
+//! try {
+//!  throw 0;
+//! } catch (_unused) {
+//!   doSomethingWhichDoesNotCareAboutTheValueThrown();
+//! }
+//! ```
+//!
+//! Output:
+//! ```js
+//! try {
+//!   throw 0;
+//! } catch (_unused) {
+//!   doSomethingWhichDoesNotCareAboutTheValueThrown();
+//! }
+//! ```
+//!
+//! ## Implementation
+//!
+//! Implementation based on [@babel/plugin-transform-optional-catch-binding](https://babel.dev/docs/babel-plugin-transform-optional-catch-binding).
+//!
+//! ## References:
+//! * Babel plugin implementation: <https://github.com/babel/babel/tree/main/packages/babel-plugin-transform-optional-catch-binding>
+//! * Optional catch binding TC39 proposal: <https://github.com/tc39/proposal-optional-catch-binding>
+
 use std::cell::Cell;
 
 use oxc_ast::ast::*;
@@ -7,11 +41,6 @@ use oxc_traverse::TraverseCtx;
 
 use crate::context::Ctx;
 
-/// ES2019: Optional Catch Binding
-///
-/// References:
-/// * <https://babel.dev/docs/babel-plugin-transform-optional-catch-binding>
-/// * <https://github.com/babel/babel/tree/main/packages/babel-plugin-transform-optional-catch-binding>
 pub struct OptionalCatchBinding<'a> {
     _ctx: Ctx<'a>,
 }