Update README.md for more transparency

Adds a blurb about initializing the NBT Wrapper with two options for legacy and modern versions.

Author: Foxikle

README.md

@@ -127,6 +127,12 @@ public class MyPlugin extends JavaPlugin {
     @Override
     public void onEnable() {
         menu = createExampleMenu();
+
+        // For > 1.13.2
+        ItemNbt.wrapper(new Pdc(this));
+
+        // for <= 1.13.2 (Legacy)
+        ItemNbt.wrapper(new LegacyNbt());
     }
 
     ...