docs: Document image mirrors

docs/deploying/docker.mdx

@@ -24,6 +24,15 @@ docker image pull $LINK
 
 to pull it to your machine.
 
+#### Mirrors
+
+Images are mirrored to multiple locations automatically, on a schedule:
+
+- `ghcr.io/continuwuity/continuwuity`
+- `docker.io/jadedblueeyes/continuwuity`
+- `registry.gitlab.com/continuwuity/continuwuity`
+- `git.nexy7574.co.uk/mirrored/continuwuity` (releases only, no `main`)
+
 ### Run
 
 When you have the image, you can simply run it with