Added a comment about linting in the README

README.md

@@ -67,6 +67,18 @@ Your contributions are very much welcome ! You can either request an account on
 
 Please also say if you had a printer to test your code, and which printer you've been using.
 
+### Linting
+
+If you want to contribute code, please make sure to lint the project before commiting. This helps the code keep a general structure, and avoids some commons erros and mistakes.
+
+To do so, you can run the following command :
+
+```
+black src/
+```
+
+Beware that this command *will* re-write files, so doing `git add <file>` and then `black src/` and then `git diff` to see what the linter has done is a good idea.
+
 ## Screenshots
 
 ![](src/static/images/homepage.png)