Mention that pre-commit is used to enforce LF ending and 644 permissions

doc/contributing.md

@@ -481,8 +481,8 @@ the code yourself. Before committing, run it to automatically format your code:
 make format
 ```
 
-For consistency, we also use UNIX-style line endings (`\n`) and file permission
-644 (`-rw-r--r--`) throughout the whole project.
+For consistency, we also use `pre-commit` hooks to enforce UNIX-style line endings
+(`\n`) and file permission 644 (`-rw-r--r--`) throughout the whole project.
 Don't worry if you forget to do it. Our continuous integration systems will
 warn us and you can make a new commit with the formatted code.
 Even better, you can just write `/format` in the first line of any comment in a