Documentation changes for code review location

[ctsims]

Summary

Documentation only change.

Updates internal documentation to reflect the new structure of the contribution / PR docs

Safety Assurance

• Risk label is set correctly
• All migrations are backwards compatible and won't block deploy
• The set of people pinged as reviewers is appropriate for the level of risk of the change
• If QA is part of the safety story, the "Awaiting QA" label is used
• I have confidence that this PR will not introduce a regression for the reasons below

Rollback instructions

• This PR can be reverted after deploy with no further considerations