SETUP: Wrote paragraph how to start mtredisalize.

SETUP.md

@@ -15,7 +15,7 @@ Setting up MTSatellite takes six steps:
 
 ## Backup your world
 
-MTSatellite is still young. So stop your running Minetest server and make a backup of your world 
+MTSatellite is still young. So stop your running Minetest server and make a backup of your world
 before you will start crying.
 
 ## Convert world database into interleaved format
@@ -39,7 +39,29 @@ Change `-source-backend=sqlite` to `-source-backend=leveldb` if your world is st
 Use `mtdbconverter --help` to see all options.
 
 ## Start mtredisalize
-**TODO: Write me!**
+
+`mtredisalize` is the component which serves the block data to Minetest and the `mtwebmapper` as a Redis
+server look-alike. Start it with:
+
+    mtredisalize                               \
+      -host=localhost                          \
+      -interleaved=true                        \
+      -change-url=http://localhost:8808/update \
+      -change-duration=10s                     \
+      /path/to/your/world/map.db
+
+This binds the server to localhost port 6379 the default Redis port. You can shange it with the `-port=` option.
+The `-interleaved=true` option is **mandatory** if you use the interleaved format of the database. Forgetting it
+will end up in the crying mentioned above.  
+The `-change-url=` option is a forward reference to the `mtwebmapper` server which will be notified if the
+world has changed. If it is not configured the tile re-generation is not triggered. As long as the Minetest server
+is down there will be no changes and therefore it is safe to configure it even if the `mtwebmapper` service is not
+running.  
+The `-change-duration=` option specifies the amount o time ho long the `mtredisalize` server aggregates changes
+made to the world before reporting them to `mtwebmapper`. It defaults to 30 seconds but the value can
+be increased or decreased depending how often you want to update the map. Decreasing it will increase the
+computing pressure on your system so configure it wisely.
+
 
 ## Pre-compute the map tiles with mtseeder
 **TODO: Write me!**