Remove instructions to fork a demo repo and rename

Recently added commit https://github.com/railsbridge/docs/commit/a6dc832c4c8e26a09647d15ee5e635b12819e2d9 will fail. This is because, in get_a_sticker.step, there are instructions to clone a repo and rename it. The name that a6dc832c4 instructs students to use will collide with the existing renamed fork. 

Since the fork/rename step is a somewhat non-standard workflow, and not particularly relevant to working on the front-end, I've removed it.

(also fixed some formatting problems with the following step in that file)