Added player.updateHealth documentation

doc/api.md

@@ -62,6 +62,7 @@
       - [player.spawn()](#playerspawn)
       - [player.setGameMode(gameMode)](#playersetgamemodegamemode)
       - [player.handleCommand(command)](#playerhandlecommandcommand)
+      - [player.updateHealth(health)](#playerupdatehealthhealth)
     - [Low level properties](#low-level-properties)
       - [player._client](#player_client)
     - [Low level methods](#low-level-methods)
@@ -288,6 +289,10 @@ set player gameMode to `gameMode`
 
 handle `command`
 
+#### player.updateHealth(health)
+
+update the player health.
+
 ### Low level properties
 
 #### player._client

lib/playerPlugins/pvp.js

@@ -15,12 +15,7 @@ function inject(serv, player)
   function attackEntity(entityId) 
   {
     var attackedPlayer = serv.entities[entityId].player;
-    attackedPlayer.entity.health -= 1;
-    attackedPlayer._client.write('update_health', {
-      food: attackedPlayer.entity.food,
-      foodSaturation: 0.0,
-      health: attackedPlayer.entity.health
-    });
+    attackedPlayer.updateHealth(attackedPlayer.entity.health - 1);
 
     if(attackedPlayer.entity.health==0)
       attackedPlayer._writeOthers('entity_status',{