Upcoming Go Package Store: Fix typos and editing.

As promised, I've carefully re-read my entire post and tried to edit it to the best of my ability. I'm pretty happy with most parts and have fixed up a few sections that I knew weren't expressing what I wanted to
say well.

This should be the final version, unless there are any more typos or other review suggestions.

Special thanks to @slimsag for catching typos and editing suggestions!

P.S. If you want me to squash this PR into one commit, I can definitely do that.