Fix screenshot on update sourcegraph page (#609)

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Author: enriquegh

docs/admin/updates/index.mdx

@@ -87,7 +87,7 @@ Sourcegraph upgrades take the following general form:
 
 Starting in v5.0.0, as an admin you are able to check instance upgrade readiness by navigating to the `Site admin > Updates` page. Here you'll be notified if your instance has any **schema drift** or unfinished **out of band migrations**.
 
-![Screenshot 2023-05-17 at 1 37 12 PM](https://github.com/sourcegraph/sourcegraph/assets/13024338/185fc3e8-0706-4a23-b9fe-e262f9a9e4b3)
+![Screenshot 2023-05-17 at 1 37 12 PM](https://storage.googleapis.com/sourcegraph-assets/docs/239155807-185fc3e8-0706-4a23-b9fe-e262f9a9e4b3.png)
 
 If your instance has schema drift or unfinished oob migrations you may need to address these issues before upgrading. Feel free to reach out to us at [[email protected]](mailto:[email protected]).