Make Latest/Stable Distinction Less Subtle in Documentation

[ryneeverett]

This is increasingly a problem. (#1002, #1006)

Some ideas from #1002:

I've been burned by this myself a number of times as it's quite subtle. I wonder if there's a theme or css customization we could make to make the stable/latest distinction louder. -- @ryneeverett

As a note about the docs: another option would be making stable the default when you open, although probably a theme difference, or having the version in a more prominent place is also useful. -- @ferdinandyb

[arsatiki]

Hello! I was burnt by this today because I thought I was looking at 1.8.0 documentation (as it says so at the top of the line). But the documentation is talking about development features...

It would be extremely helpful if the version number on the documentation included word 'dev' or something similar there.