Ignore the fact that the branch doesn't yet exist

Author: Xaymar

.github/workflows/documentation.yml

@@ -29,7 +29,8 @@ jobs:
         fetch-depth: 0
 
     - name: "Clone Documentation"
-      uses: actions/checkout@v3
+      continue-on-error: true
+      uses: actions/checkout@v3      
       with:      
         ref: 'documentation'
         path: 'build/docs/html'