Added provider and callback examples.

README

@@ -33,6 +33,53 @@ parameters:
     Defaults to 0.5 seconds.
 
 
+Providers
+=========
+
+You can register providers which allow to customize the spawn point of
+the players. The provider is a callback that is able to provide a different
+spawn point. The signature is:
+
+    function(
+        player,    -- The Player object of the player that is going to respawn.
+        spawn_pos) -- The current spawn position of the player.
+    
+    returns
+        spawn_pos  -- The position at which the player should ge respawned.
+                   -- nil to use the current one.
+
+And a usage example:
+
+    -- Fixes the spawn point of the player named "hero" at some position.
+    spawnusher.register_spawnpoint_provider(function(player, spawn_pos)
+        if player:get_player_name() == "hero" then
+            return {
+                x = 0,
+                y = 125,
+                z = 50
+            }
+        end
+    end)
+
+
+After Spawn Callbacks
+=====================
+
+You can register a callback that will be invoked after the player has been
+respawned. This callback can't modify the spawn point anymore and is only
+to get informed about the actual spawn point of the player. The signature is:
+
+    function(
+        player,      -- The Player object of the player that has respawned.
+        spawn_point) -- The spawn point of the player.
+
+Usage example:
+
+    spawnusher.register_after_spawn_callback(function(player, spawn_point)
+        -- Do something with this information.
+    end)
+
+
 Caveats
 =======