Update Installation.md

Add note about multiple folders.

docs/Installation.md

@@ -51,6 +51,19 @@ The default port is 6363, so unless you've changed that, once the server is up a
 Other options:
 `SYNO_THUMBS=True` - Tells Damselfly to use existing Synology thumbnails (which are generated by DSM's indexing process) and to generate new thumbs in the same format.
 
+## Support for Multiple Root Folders
+
+Damselfly works by scanning the entire directory tree under one top-level folder. However, some people may have multiple folders - some on different mounts/shares - they want to include in their library. If you want this, the simplest way is to mount them as subfolders under the /pictures folder in the docker container.
+
+```
+         volumes:
+            - /volume1/dockerdata/damselfly:/config
+            - /volume1/dockerdata/damselfly/thumbs:/thumbs
+            - /volume1/photo:/pictures/photos
+            - /volume2/otherimages:/pictures/other
+            - /volume2/familypics:/pictures/familypics
+```
+            
 ## FileWatcher INotify Limits
 
 Damselfly uses OS-level filewatcher triggers to monitor your library for changes. One watcher is created for each folder in your