Simple pre-commit hook for usort

Issue #260

ghstack-source-id: 1081271f25de255bedf5c2603647762f45dcf9cc
Pull Request resolved: #261

.pre-commit-hooks.yaml

@@ -0,0 +1,9 @@
+- id: usort
+  name: Sort imports with µsort
+  description: Safe, minimal import sorting
+  language: python
+  types_or:
+    - python
+    - pyi
+  entry: usort format
+  require_serial: true

README.md

@@ -84,7 +84,20 @@ To just validate that files are formatted correctly, like during CI:
 $ usort check <path>
 ```
 
-# License
+### pre-commit
+
+µsort provides a [pre-commit](https://pre-commit.com/) hook. To enforce sorted
+imports before every commit, add the following to your `.pre-commit-config.yaml`
+file:
+
+```yaml
+- repo: https://github.com/facebook/usort
+  rev: v1.0.7
+  hooks:
+    - id: usort
+```
+
+## License
 
 μsort is MIT licensed, as found in the [LICENSE][] file.