docs: set KVERSION for running test suite

[bdrung]

Changes

Running the test suite in podman will most likely require setting KVERSION because the running Linux kernel version will most likely be different to the kernel version in the container.

Checklist

• [x] I have tested it locally
• [x] I have reviewed and updated any documentation if relevant
• [ ] I am providing new code and test(s) for it

[LaszloGombos]

My plan is to improve https://github.com/dracutdevs/dracut/blob/master/tools/test-github.sh and document the use of https://github.com/dracutdevs/dracut/blob/master/tools/test-github.sh in docs/HACKING.md.

We should probably rename test-github.sh .

We should probably teach test-github.sh to only set KVERSION is needed (e.g. by detecting containerization).

If there is interest for a quick win in the documentation, I do not mind landing this PR as is.

@bdrung WDYT ?

[bdrung]

The test-github.sh is just another layer of indirection: test-github.sh -> test/Makefile -> test/TEST-$x/Makefile -> test/Makfile.testdir -> ./test.sh. Maybe test/Makefile could set KVERSION depending on what is available.

A quick win for the documentation is useful even when you rework test-github.sh tomorrow.