Merge branch 'git-help' into 'main'

Add guide for fixing broken master/main

See merge request 2009scape/contributor-wiki!2

Git-Basics.md

@@ -125,3 +125,18 @@ git push --force origin cider
 
 4) If you've lost something you did not backup you can use ```git checkout {hash}``` to try and find the pieces.
 
+## Undoing updating a local master
+It's possible at some point you accidently update your master branch. This will cause you problems. Before you do this you will need to temporarly allow [force pushing](https://docs.gitlab.com/ee/user/project/protected_branches.html#allow-force-push-on-a-protected-branch) to your master branch. Make sure to turn it off afterwards.
+
+1) Get the latest upstream files
+```
+git fetch -ap upstream
+```
+2) Reset your master branch. **Warning you will lose any locally changed files that are only on master!**
+```
+git reset --hard upstream/master
+```
+3) Push to your master branch
+```
+git push origin master --force
+```