Document remote_media setting

minetest.conf.example

@@ -239,6 +239,10 @@
 #congestion_control_aim_rtt = 0.2
 #congestion_control_max_rate = 400
 #congestion_control_min_rate = 10
+# Specifies URL from which client fetches media instead of using UDP
+# $filename should be accessible from $remote_media$filename via cURL
+# (obviously, remote_media should end with a slash)
+# Files that are not present would be fetched the usual way
 #remote_media =
 
 # Mapgen stuff