Lua_api.txt: Clarify use of looping sounds

doc/lua_api.txt

@@ -441,15 +441,21 @@ from the available ones of the following files:
 
 Examples of sound parameter tables:
 
-    -- Play location-less on all clients
+    -- Play locationless on all clients
     {
         gain = 1.0, -- default
     }
-    -- Play location-less to a player
+    -- Play locationless to one player
     {
         to_player = name,
         gain = 1.0, -- default
     }
+    -- Play locationless to one player, looped
+    {
+        to_player = name,
+        gain = 1.0, -- default
+        loop = true,
+    }
     -- Play in a location
     {
         pos = {x = 1, y = 2, z = 3},
@@ -461,9 +467,12 @@ Examples of sound parameter tables:
         object = <an ObjectRef>,
         gain = 1.0, -- default
         max_hear_distance = 32, -- default, uses an euclidean metric
-        loop = true, -- only sounds connected to objects can be looped
+        loop = true,
     }
 
+Looped sounds must either be connected to an object or played locationless to
+one player using `to_player = name,`
+
 ### `SimpleSoundSpec`
 * e.g. `""`
 * e.g. `"default_place_node"`