Add a section, under the provisional name "Baby Steps" to describe a minimal process for editing/contributing. Basically just create an account on GitLab, fork openmw there, then edit the relevant document to create Merge Request
A subsequent MR will suggest moving most of this to a separate document for intermediate-level contributors, and replacing it with much simpler instructions for beginners - basically edit directly on GitLab as suggested by Psi29a on the forum here - https://forum.openmw.org/viewtopic.php?f=43&p=56458#p56457
