Fix CLOSED_CONTRIBUTIONS.md (#586)

The steps dont work without this change

Author: JTorreG

CLOSED_CONTRIBUTIONS.md

@@ -33,7 +33,7 @@ To create closed content, add the closed repository as a remote to the main repo
 ```shell
 cd documentation
 git remote add internal [email protected]:<closed-url>.git
-git fetch
+git fetch --all
 ```
 
 Check out the remote `main` branch, and use it to create a feature branch. **Ensure that you prefix all branch names with `internal/`**
@@ -64,4 +64,4 @@ git merge internal/internal/feature
 git push origin
 ```
 
-Once the content changes have been merged in the open repository, they will synchronize back to the closed repository.
+Once the content changes have been merged in the open repository, they will synchronize back to the closed repository.