Create Training Module: Get Started with code MRs

This should be similar to our documentation training where we're "guiding" the experience rather than putting any substantial information.

Things to cover:

• reading through the development docs including some of the below points
• commit message guidelines
• spec updates
• rubocop and other local tests to run
• labelling MR, especially support related ones
• changelog / guidelines
• Code Review Guidelines
• how to decide to assign a merge request to someone for review
• feature flags specific info
• testing your MR once it goes live (staging, self-managed Omnibus dev packages)