add git ex advice

[james-bruten-mo]

PR Summary

Code Reviewer: @jennyhickson

Using suites on the EXs, someone has run into an error due to not setting their user and email. Add some advice to include that in the WPs.

Code Quality Checklist

• I have performed a self-review of my own code
• I have locally built the documentation successfully, and the output of changed sections is as expected

Code Review

• The changes are coherent and valid