Add link to License Manager upgrade page at start of migration guide

Author: hach-que

docs/support/migrate.mdx

@@ -6,6 +6,10 @@ description: Learn how to migrate your project from Online Subsystem Blueprints
 
 If you previously used the Online Subsystem Blueprints or Matchmaking plugins, and are now upgrading to the EOS Online Framework, you'll need to migrate your project.
 
+## Upgrade your license
+
+If you don't yet have access to EOS Online Framework in Fab or GitLab, use the [upgrade page in the License Manager](https://licensing.redpoint.games/upgrade) to switch your license over.
+
 ## Close the editor
 
 Close the editor if it is already open.