Improve navigation after selecting version range

I am not sure why the app changes to a new route after selection the desired version range, but when using the site I found myself looking for a way to go back to the previous page, or somehow edit the version range. It was only after a long while that I noticed there is a "Return to Homepage" link at the very bottom of the page, which is harder to get to the bigger the version range.

I am not marking this issue as "help wanted" for now as I don't have a concrete suggestion on how to address this, but if you're reading this and are interested in exploring the issue and contributing, please go right ahead!

## Tasks
- [ ] Change "Return to Homepage" text at bottom of upgrading page to "Go back"
- [ ] Show version selectors in upgrading page