Changes for updates to Scratch 2.0 CodeClub Term 1

Hey @topshed! So I proofread your updates to your half of Term 1, and updated some things. The diff looks massive because there are a bunch of formatting things I added (mostly adding classes to scratch blocks in the main text), there are hardly any actual changes!
Wasn't sure if this was the best format for the changes so we can merge our work together, but at least this gets us a diff to work with - LMK what you think :)