Document additionalHooks option (#19005)

* Document `additionalHooks` option

* Update README.md

Co-authored-by: Aaron Pettengill <aaron.pettengill@echoman.com>
Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

packages/eslint-plugin-react-hooks/README.md

@@ -48,6 +48,24 @@ If you want more fine-grained configuration, you can instead add a snippet like
 ```
 
 
+## Advanced Configuration
+
+`exhaustive-deps` can be configured to validate dependencies of custom Hooks with the `additionalHooks` option.
+This option accepts a regex to match the names of custom Hooks that have dependencies.
+
+```js
+{
+  "rules": {
+    // ...
+    "react-hooks/exhaustive-deps": ["warn", {
+      "additionalHooks": "(useMyCustomHook|useMyOtherCustomHook)"
+    }]
+  }
+}
+```
+
+We suggest to use this option **very sparingly, if at all**. Generally saying, we recommend most custom Hooks to not use the dependencies argument, and instead provide a higher-level API that is more focused around a specific use case.
+
 ## Valid and Invalid Examples
 
 Please refer to the [Rules of Hooks](https://reactjs.org/docs/hooks-rules.html) documentation and the [Hooks FAQ](https://reactjs.org/docs/hooks-faq.html#what-exactly-do-the-lint-rules-enforce) to learn more about this rule.