Merge pull request #5735 from jbampton/pre-commit-skip-docs

Add docs on the `SKIP` pre-commit environment variable

CONTRIBUTING.md

@@ -33,9 +33,14 @@ To run a single hook use `pre-commit run --all-files <hook_id>`
 
 To update use `pre-commit autoupdate`
 
+Sometimes you might need to skip one or more hooks which can be done with the `SKIP` environment variable.
+
+`$ SKIP=yamllint git commit -m "foo"`
+
 * [Quick start](https://pre-commit.com/#quick-start)
 * [Usage](https://pre-commit.com/#usage)
 * [pre-commit-autoupdate](https://pre-commit.com/#pre-commit-autoupdate)
+* [Temporarily disabling hooks](https://pre-commit.com/#temporarily-disabling-hooks)
 
 ## Spell Checking