docs: add pre-commit sample output

Author: lpm0073

DEVELOPER_SETUP.md

@@ -23,6 +23,10 @@ pre-commit autoupdate
 pre-commit run --all-files
 ```
 
+Output should look similar to the following:
+
+![pre-commit output](./doc/pre-commit.png)
+
 ### Github Secrets
 
 The GitHub Actions automated processes depend on several credentials which are stored inside of Github Secrets. When creating pull requests, the GitHub Actions will use these secrets, [github.com/FullStackWithLawrence/aws-openai/settings/secrets/actions](https://github.com/FullStackWithLawrence/aws-openai/settings/secrets/actions), so there's nothing special for you to do.

doc/pre-commit.png

@@ -1,2 +1,3 @@
 #!/bin/bash
+# Called from pre-commit. Run pylint on all python files in the current directory
 python -m pylint "$@"