docs: update info about root option

Author: mrexox

docs/configuration.md

@@ -963,6 +963,8 @@ You can change the CWD for the command you execute using `root` option.
 
 This is useful when you execute some `npm` or `yarn` command but the `package.json` is in another directory.
 
+For `pre-push` and `pre-commit` hooks and for the custom `files` command `root` option is used to filter file paths. If all files are filtered the command will be skipped.
+
 **Example**
 
 Format and stage files from a `client/` folder.