may add --user argument in doc when running local

I propose to add the --user argument in the documentation, when running local. For example:

$ docker run -v $(pwd):/repo --user $(id -u):$(id -g) gitext.gfz-potsdam.de:5000/software/services/fair/ci-services/ci-services:latest --generate-report

So the created ./meta folder is not owned by root.