Add demo

Author: wchen-r7

documentation/modules/exploit/multi/misc/openoffice_document_macro.md

@@ -47,6 +47,10 @@ Once started, the module will mainly do these things:
 
 This option can be used to insert text to the malicious document.
 
+## Demo
+
+![openoffice_macro_demo](https://cloud.githubusercontent.com/assets/1170914/22761020/9e7667ca-ee1e-11e6-9fc1-a29c55f405f0.gif)
+
 ## Modification
 
 Since social engineering will play a big part in the success of the attack, you will most likely