Removed the warning about persist

This was likely fixed in 4.0.0.

Author: EddyVerbruggen

docs/DATABASE.md

@@ -11,8 +11,6 @@ Since this is the most likely feature you'll use with this plugin it has already
 ### init
 You can optionally pass `persist` to the [`init` function](../README.md#init) to make Firebase save data to the local disc so it will work in offline scenario's. Default `false`.
 
-> Beware that `persist` [may cause trouble](https://github.com/EddyVerbruggen/nativescript-plugin-firebase/issues/186#issuecomment-265276766) when using `livesync`.
-
 ```js
   firebase.init({
     persist: true