Add dev setup to CONTRIBUTING.md

CONTRIBUTING.md

@@ -26,6 +26,14 @@ and will result in us having to ask you to fill out the missing information or c
 That's the high level flow of it. Note that this repo uses merge commits so don't feel the need to squash your commits
 before your pr.
 
+### Dev setup
+
+This project is managed via poetry so setup should be just running `poetry install`.
+
+This repo is using [`pre-commit`](https://pre-commit.com/) to setup some checks to happen at commit time to keep the
+repo clean. To set these up after you've run `poetry install` just run `poetry run pre-commit install` to have
+pre-commit setup these hooks
+
 ## Coding Guidelines
 
 ### Formatting