Fix description copy

Make the naming of "Librem 5" consistent and in line with marketing.

* Space between "Librem" and "5"
* Capitalise "Librem"
* Consistency in full stops on the end of sentences
1 job from librem5-gnome-phone in 43 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #4115
librem5
build-debian-package

00:00:43