warn about upgrading past 2024.3.1 with Docker

content/en/docs/install/fresh.md

@@ -240,6 +240,17 @@ instructions](https://misskey-hub.net/en/docs/admin/nginx.html)
 
 ## Update Sharkey
 
+### With Docker
+
+Fetch the latest image, restart.
+
+**NOTE**: if you are upgrading from 2024.3.1 or earlier, and are *not*
+using S3 or similar, you will have to `chown -R 991:991
+Sharkey/files/`, otherwise uploads won't work anymore. This is because
+previous versions ran Sharkey as the root user, but we no longer do that.
+
+### Manually
+
 Very similar to the installation process:
 
 ```bash