Add beta page for pre-release versions
The intention for this page is to confirm that a user has updated to a pre-release version of Plasma, and to signpost where they can go to see what's new, and report bugs.
This will apply for upgrades to beta versions (.90) in the Plasma 6 series, and the current Plasma 6 alpha, beta and RC releases. It will NOT show itself for development versions (.80).
Recommendations for changing the description text are more than welcome.
Fixes #23 (closed)
Edited by Oliver Beard