docs(CONTRIBUTING): add section on how to install pre-commit hooks

.pre-commit-config.yaml

@@ -16,7 +16,6 @@ repos:
   rev: master
 - hooks:
   - id: commitizen
-    stages:
-    - commit-msg
+    stages: [commit-msg]
   repo: https://github.com/commitizen-tools/commitizen
-  rev: v2.1.0
+  rev: master

CONTRIBUTING.md

@@ -25,7 +25,7 @@ The `description` is a decriptive summary of the change the PR will make.
 
 - All PRs should be rebased (with master) and commits squashed prior to the final merge process
 - One PR per fix or feature
-- Setup & install [pre-commit hooks](https://pre-commit.com/#install)
+- Setup & install [pre-commit hooks](https://pre-commit.com/#install) then install the hooks `pre-commit install && pre-commit install --hook-type commit-msg`
 
 ### Git Commit Message Style