In 18db7e679f the Dockerfile write
permissions were removed to help remind the new contributor that they
should not be modified. However git does not keep that information (it
only keeps the executable bit in the file permissions), therefore
someone with a fresh clone will not have a file that is read-only.
Removing the write permission will however be a problem for anyone
running the update.sh script twice: it will fail to remove the files
because it uses rm -r instead of rm -fr.
Instead of fixing the removale to use the force flag, we revert the
modification that remove the write permission since it does not
actually help anyone.
The `*/*/Dockerfile` are created from `Docker*template` by the
update.sh script. We add a comment at the beginning of the file with
information to find their origin. We also make them readonly to remind
people who would like to improve these files that they are not meant
to be modified.
This is necessary in order to have proper generation of variant and
version-based Dockerfiles from a single template.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>