Document in README how to launch web app

README.md

@@ -2,10 +2,11 @@
 
 Tools to manage an UltraStar DX song library. Features include:
 
-1. Deduplication
-2. Organization
-3. Recoding
-4. Jsonification
+1. Web-based catalogue UI
+2. Deduplication
+3. Organization
+4. Recoding
+5. Jsonification
 
 ## Setup
 
@@ -23,6 +24,18 @@ We assume that your song library is stored at `$SONG_LIBRARY`. Replace this plac
 export SONG_LIBRARY=/path/to/library
 ```
 
+### Web-based catalogue UI
+
+**Launch server for a web-based UI to browse the catalogue**, supporting to create a list of favorites.
+
+ℹ️ This is completely risk-free, as it does not change files.
+
+```bash
+python3 -m karaokatalog.ui.serve $SONG_LIBRARY
+```
+
+To speed up the start, use jsonification to create and persist a JSON of all songs in the library root dir before starting this UI. 
+
 ### Deduplication
 
 **Find and delete exactly duplicated songs**, i.e., songs with the same title and artist that also consist of exactly the same files in the directory.