While AppImage attempts to be a more portable way of running
applications across linux installations, sometime is maybe necessary
to run inside docker.
So examples are provided, which also provides testing regime to
validate how the AppImage can be quickly tested.
This switches the 'remotes/origin/HEAD' and uses the current HEAD of the
current checked out git repo.
Revised the sed rule that is transforming (to be more specific on the
matching regex /-\d+-g/ than just the first /-/):
8.3.530-7-gb64321d4 => 8.3.530+7-gb64321d4 (replace first '-' with '+'
to indicate it is tag plus this many commits)
8.3.530 => 8.3.530 (no change)
This switches to the 'continuous' tag release, that will auto update.
This broke the very old AppImage7 tool since that release not return
HTTP/404. But I updated all to use their current recommendation.