Add docs for bugfix-firefox-class-in-computed-class-key (#2885)

docs/plugin-bugfix-firefox-class-in-computed-class-key.md

@@ -0,0 +1,45 @@
+---
+id: babel-plugin-bugfix-firefox-class-in-computed-class-key
+title: "@babel/plugin-bugfix-firefox-class-in-computed-class-key"
+sidebar_label: bugfix-firefox-class-in-computed-class-key
+---
+
+This bugfix plugin transforms classes inside computed keys of other classes to workaround a [SpiderMonkey bug](https://bugzilla.mozilla.org/show_bug.cgi?id=1887677) with private class elements.
+
+:::tip
+This plugin is included in `@babel/preset-env`, and Babel will automatically enable this plugin for you when your `targets` are affected by the browser bug.
+:::
+
+:::warning
+Terser versions older than 5.30.2 will undo the transform done by this plugin. Make sure to use at least version 5.30.2, or set the Terser's [`compress.inline`](https://terser.org/docs/options/#compress-options) option to `false`.
+:::
+
+## Installation
+
+```shell npm2yarn
+npm install --save-dev @babel/plugin-bugfix-firefox-class-in-computed-class-key
+```
+
+## Usage
+
+### With a configuration file (Recommended)
+
+```json title="babel.config.json"
+{
+  "plugins": ["@babel/plugin-bugfix-firefox-class-in-computed-class-key"]
+}
+```
+
+### Via CLI
+
+```sh title="Shell"
+babel --plugins @babel/plugin-bugfix-firefox-class-in-computed-class-key script.js
+```
+
+### Via Node API
+
+```js title="JavaScript"
+require("@babel/core").transformSync("code", {
+  plugins: ["@babel/plugin-bugfix-firefox-class-in-computed-class-key"],
+});
+```

website/sidebars.js

@@ -152,6 +152,7 @@ module.exports = {
               type: "category",
               label: "Bugfix",
               items: [
+                "babel-plugin-bugfix-firefox-class-in-computed-class-key",
                 "babel-plugin-bugfix-safari-id-destructuring-collision-in-function-expression",
                 "babel-plugin-bugfix-v8-spread-parameters-in-optional-chaining",
               ],