Add doc on dependencies needed for the jenkins slave running osmo-gsm-tester-gerrit job
A new jenkins slave was recently added and job checking osmo-gsm-tester commits in gerrit (osmo-gsm-tester-gerrit) is failing because it's missing some python yaml module installed.
We should add documentation on what needs to be installed in he jenkins slave in order to be able to run that job in here:
Maybe take the time too to check that all dependencies are well described in README in osmo-gsm-tester repo as well as in the osmo-gsm-manuals repo.
Affected build node: build2-deb8build