Update README.md

Vundle no longer uses "Bundle" it is deprecated and is now called "Plugin"
Therefore:
Bundle "sudar/vim-arduino-syntax"   ---->   Plugin 'sudar/vim-arduino-syntax'
BundleInstall     ---->     PluginInstall

Author: z3t0

README.md

@@ -16,9 +16,9 @@ Using [Vundle](https://github.com/gmarik/vundle)
 
 ```VimL
 
-    Bundle "sudar/vim-arduino-syntax"
+    Plugin "sudar/vim-arduino-syntax"
 
-    And :BundleInstall
+    And :PluginInstall
 
 ```
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