Changes

jobs/README: convert to markdown

Convert to markdown, so it gets rendered in gitea.

Change-Id: I0b687b651b44c798d5d224b0a3ea734b1bc41dff

jenkins-jobs-osmo: new file

Do not recommend to the user anymore to put the Osmocom jenkins server
in their global jenkins-job-builder config, as this may lead to jobs
from other repositories being deployed to the Osmocom jenkins by
accident.

Instead of that, let the user put the config in this path:
	~/.config/jenkins_jobs/jenkins_jobs_osmo-ci.ini

Add a wrapper script that users this path, and makes sure that no global
config is present.

Related: SYS#6957
Change-Id: I1d7c50b2fef56e343cfe377b51f5f4304219cd22