Plasma/5.12 branches made

[Jonathan Riddell]

I've made new stable branches for Plasma 5.12 for these repos
https://cgit.kde.org/releaseme.git/tree/plasma/git-repositories-for-release

Please make bugfixes to these branches
Tars and Tag is due Thu 1 Feb for final release on Tue 6th

i18n dudes could you set the new stable branch for translations.  This
will be an LTS release but we still have another 5.8 LTS scheduled so
I think leave the LTS translations until that's out.

Jonathan