(cherry picked from commit 4a6cbab2)

Krita 5.0 includes the built-in update mechanism for AppImages. The
release CI job will provide one more file: the zsync metadata file
needed for the update mechanism to work.

The zsync metadata file is mentioned in the list of files to upload to
download.kde.org in step 12 and the total number of files is updated.

The tutorial got changed to use Krita's Colorize mask, so make it consistent.

This is the first step in activating the translations.

The animation UI and code has been changed to use the pinning
terminology for displaying inactive layers on the timeline.
I've updated the docs to reflect this change as well as made
a couple of small, related edits to the animation docs.

Also fix a faulty entry.

This commit contains a list of things to do when you want to get the best user support. It's more like a wishlist than anything.

Except for that, the commit also includes several smaller changes throughout the page.

Before this commit, there was only information about getting
the backtrace from Krita on Windows in the manual.
This commit adds information:
- how to get a backtrace on Mac and Linux
- how to get a text output from Krita
- how to get a Krita usage log