Update README.md

Add v2 screenshot

Author: samiraguiar

README.md

@@ -1,6 +1,10 @@
 # MantisBT Issues Diff
 MantisBT Plugin to get a visual diff between issues revisions.
 
-![issues diff plugin](http://i.imgur.com/STu5oHB.png)
+### For MantisBT v2
+![issues_diff_plugin_v2](http://i.imgur.com/ZVfeFLt.png)
 
-Copyright (C) 2017 Samir Aguiar for Intra2net AG - www.intra2net.com
+### For MantisBT v1
+![issues diff plugin_v1](http://i.imgur.com/STu5oHB.png)
+
+Copyright (C) 2017 Samir Aguiar for Intra2net AG - www.intra2net.com