Document some culprits with pre-commit (#1783)

* Document some culprits with pre-commit

* make pre-commit happy

* don't use monospace for black & pre-commit

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

* make pre-commit happy again

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

docs/version_control_integration.md

@@ -23,6 +23,11 @@ for your project. See _Black_'s own
 [pyproject.toml](https://github.com/psf/black/blob/master/pyproject.toml) for an
 example.
 
+When using the `--diff` flag with `pre-commit`, you must also use the `--check` flag.
+When you want to run _Black_ only on specific files in pre-commit, either use
+pre-commit's own `files` and `exclude` or, when using _Black_'s `--include`, set
+`--force-exclude` to the negated regex of `--include`.
+
 If you're already using Python 3.7, switch the `language_version` accordingly. Finally,
 `stable` is a branch that tracks the latest release on PyPI. If you'd rather run on
 master, this is also an option.