Merge/update a forked git repository
First add the "upstream" remote:
git remote add upstream remote_repo
Then fetch it:
git fetch upstream
Merge it with your local code:
git merge upstream/main
Resolve any possible conflicts (i.e. go through each file and edit it as necessary), commit and push them, and you're done!
Hopefully github's network graph will show you a nicely updated graph in your timeline ;)
