Finish and proofread all map submission related text

[tsa96]

Various bits of text on the frontend explaining map submission stuff are still unfinished, or need linking to docs pages that haven't been made yet.

Also, I have a really terrible habit of writing really unnecessarily wordy sentences, and I use words like "really" too far much. Someone else proofreading what I have would be helpful.

Let's do this round the time we get map submission/porting guidelines docs pages made.