doc(API): describe 'enableLipSync' option

doc/API.md

             - muc
             - anonymousdomain
         3. useStunTurn -
+        4. enableLipSync - (optional) boolean property which enables the lipsync feature. Currently works only in Chrome and is enabled by default.
 
 2. connect(options) - establish server connection
     - options - JS Object with ```id``` and ```password``` properties.