Editions can be marked as being in beta

www.agileplannerapp.com/boards/173808/cards/5418

As a GDS content designer
I want to show GOV.UK end users that a piece of
mainstream content is not yet the official source
and is still in beta
So that I can trial content with the public and
gather evidence to make it even better

cc: @fofr
The link is also a slightly different colour grey to the help text, you can use the class `link-inherit` to inherit the colour of the surrounding text, rather than `link-muted`.