docs(applicationset): add section explaining how to set up repo crede…

…ntials for git generator

Signed-off-by: Rune Antonsen <[email protected]>

docs/operator-manual/applicationset/Generators-Git.md

@@ -443,3 +443,9 @@ stringData:
 ```
 
 After saving, please restart the ApplicationSet pod for the changes to take effect.
+
+## Repository credentials for ApplicationSets
+If your [ApplicationSets](index.md) uses a repository where you need credentials to be able to access it, you need to add the repoistory as an "non project scoped" repository.  
+- In the UI, this is the "blank" value in the dropdown menu.
+- For CLI, make sure you DO NOT supply the parameter `--project` ([argocd repo add docs](../../user-guide/commands/argocd_repo_add.md))
+- For YAML spec, make sure you DO NOT have `project:` defined under `stringData:` ([complete yaml example](../argocd-repositories-yaml.md))