Frontend/Backend - Platform - Update `README.md` to reflect updated contribution section

Ended up finding an issue with our Commit message convention, can't believe I didn't realise this sooner, since we've put the issue number at the start of a commit when doing an interactive rebase.

Also I think we should add a section on branch naming and probably how to do merge requests, scares me that people might be creating empty MRs and then pushing to the created branch - god save our pipelines.