Grammar tweaks, minor rewriting

No factual changes, only did rewrites on a few unclear phrases or sections that could be improved.
Do you mean the "(NB: Replace 'TOKEN' for the..." line? If so, I got that phrasing form the middle of the original line 7 "(NB: Swap TOKEN for the token from step 1, and B..." and just make the instructions a little more clear – it's how to modify the URL to work with your Trello board, but maybe it's still not clear enough.

I'm not sure what "NB" refers to, to be honest, but I assumed it was a usage shorthand I wasn't familiar with.