Add quick-start-contribution-onboarding.rst and improve gitlab.rst

@kristis and I prepared documentation file which describes how to contribute to the Oniro Project

Closes #150 (closed)

Signed-off-by: Grzegorz Gwóźdź grzegorz.gwozdz@huawei.com

index.rst

@@ -72,6 +72,7 @@ daily life.
 
    meta-openharmony/supported-technologies/openharmony
    oniro/supported-technologies/openthread
+   oniro/supported-technologies/containers
 
 .. toctree::
    :caption: Troubleshoot