Pre-commit + blame ignore revs of black+isort setup

.git-blame-ignore-revs

@@ -0,0 +1,4 @@
+# Black
+d57c1831257a98b6ef1280c25c787598879074fb
+# isort
+ba63870c890c6b91862e35adb188b9c51dd75b0e

.pre-commit-config.yaml

@@ -0,0 +1,13 @@
+repos:
+-   repo: local
+    hooks:
+    -   id: black
+        name: black
+        entry: black
+        language: system
+        types: [python]
+    -   id: isort
+        name: isort (python)
+        entry: isort
+        language: system
+        types: [python]

README.md

@@ -63,3 +63,17 @@ Add something like this:
 ### Install initial data
 
 `python manage.py loaddata polybookexchange_epfl.yaml`
+
+## Contributing
+The code is formatted using [black](https://github.com/psf/black) and [isort](https://github.com/pycqa/isort). You can install the tools with
+```
+pip install black isort
+```
+
+You can run the formating by running
+```
+$ black
+$ isort
+```
+
+To run the formatters in the pre-commit hook, install pre-commit (`pip install pre-commit`) and run `$ pre-commit install` at the root of the repository