Update Upgrade_Toolkit.md

Author: Lasyavns

cd3_automation_toolkit/documentation/user_guide/Upgrade_Toolkit.md

@@ -16,5 +16,6 @@
 <br><br>
 <div align='center'>
 
-| <a href="/cd3_automation_toolkit/documentation/user_guide/NetworkingScenariosNGF.md">:arrow_backward: Prev</a> | <a href="/cd3_automation_toolkit/documentation/user_guide/RestructuringOutDirectory.md">Next :arrow_forward:</a> |
-| :---- | -------: |
+| <a href="/README.md#table-of-contents-bookmark">Main menu</a> |
+| :---- | 
+ </div>