Update readme

Author: mathcantin

README.md

@@ -1,8 +1,10 @@
 # Dockerfile lint pre-commit
 
+This project add hooks to run [hadolint](https://github.com/hadolint/hadolint) with the [pre-commit](https://pre-commit.com/) project.
+
 ```bash
 - repo: https://github.com/petalmd/dockerfile-pre-commit
-  rev: ''  # Use the revision sha / tag you want to point at
+  rev: ''  # Use the revision rev you want to point at
   hooks:
   - id: dockerlint
 ````