Code Suggestion docs - clarify top-level groups
What does this MR do and why?
Describe in detail what your merge request does and why.
We are getting questions about how this works with Parent and Child groups, this aims to add clarity in how these features work with different levels of groups. This updates the existing documentation here: https://docs.gitlab.com/ee/user/project/repository/code_suggestions.html
Edited by Taylor McCaslin