[ FLOC-1010] Improvements to the release process documentation

Fixes https://clusterhq.atlassian.net/browse/FLOC-1010
IIRC past comments (from @tomprince maybe) have said that the `$` character is useful to show that it is a shell command. The `$` is removed in multi-line statements because although it makes it less clear that it is a shell command, copy-pasting multiple commands is made easier.