Update README.md to use new Vundle syntax

Vundle now uses `Plugin` instead of `Bundle`
diff --git a/README.md b/README.md
index 18cc96c..390cafc 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@
 
 *  [Vundle](https://github.com/gmarik/vundle)
 
-		Bundle 'GutenYe/json5.vim'
+		Plugin 'GutenYe/json5.vim'
 
 *  [Pathogen](https://github.com/tpope/vim-pathogen)