add compat-data docs

docs/compat-data.md

@@ -0,0 +1,55 @@
+---
+id: babel-compat-data
+title: "@babel/compat-data"
+---
+
+This package provides compatibility data for various JavaScript features across different browser and runtime environments. It is used by [`@babel/preset-env`](./preset-env.md) internally to determine the required Babel plugins for given [compilation targets](./options.md#targets). The compat data is extracted from the [compat-table project](https://github.com/compat-table/compat-table).
+
+## Install
+
+```shell npm2yarn
+npm install --save-dev @babel/compat-data
+```
+
+## Usage
+
+### plugins
+```javascript title="my-babel-plugin.js"
+import _plugins from "@babel/compat-data/plugins";
+const pluginsCompatData = _plugins.default;
+```
+
+The `pluginsCompatData` is an object with the Babel plugin short name as key and a compat data entry as value. Each entry is an object with browser name as key and the minimum supported version as value.
+
+For example, `pluginsCompatData["transform-object-rest-spread"]` will return an object:
+
+```javascript title="my-babel-plugin.js"
+{
+    "chrome": "60",
+    "opera": "47",
+    "edge": "79",
+    "firefox": "55",
+    "safari": "11.1",
+    "node": "8.3",
+    "deno": "1",
+    "ios": "11.3",
+    "samsung": "8",
+    "opera_mobile": "44",
+    "electron": "2.0"
+}
+```
+Here, the minimum Chrome version with object-rest-spread support is `60`. Therefore, `@babel/preset-env` will enable the object-rest-spread transform only if users are compiling to Chrome versions older than `60`, and likewise for other browsers. Check the [source](https://github.com/babel/babel/blob/main/packages/babel-compat-data/data/plugins.json) for supported Babel plugin short names.
+
+If you would like to know whether object-rest-spread is supported for any given `targets`, you don't have to manually compare it against the compat-data entry. Instead, you can use the [`isRequired`](./helper-compilation-targets.md#isrequired) utility from `@babel/helper-compilation-targets`:
+
+```javascript title="my-babel-plugin.js"
+import { isRequired } from "@babel/helper-compilation-targets";
+
+module.exports = api => {
+  // Check if the targets have native object-rest-spread support
+  const objectRestSpreadSupported = !isRequired(
+    "transform-object-rest-spread",
+    api.targets()
+  );
+};
+```

website/sidebars.js

@@ -225,6 +225,7 @@ module.exports = {
         "babel-parser",
         "babel-core",
         "babel-generator",
+        "babel-compat-data",
         "babel-code-frame",
         "babel-runtime",
         "babel-template",