Fix typos in CONTRIBUTING.md

Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>

CONTRIBUTING.md

@@ -2,9 +2,9 @@
 
 Patches should be sent to the [aur-dev@archlinux.org][1] mailing list.
 
-Before sending patched you are recomended to run the `flake8` and `isort`.
+Before sending patches, you are recommended to run `flake8` and `isort`.
 
-You can add git hook to do this by installing `python-pre-install` and running
-`pre-install install`.
+You can add a git hook to do this by installing `python-pre-commit` and running
+`pre-commit install`.
 
 [1] https://lists.archlinux.org/listinfo/aur-dev