Update 3.0.md

added social media example

Author: micheldumontier

versions/3.0.md

@@ -1032,6 +1032,8 @@ Field Name | Type | Description
   url: http://example.org/api/docs
 - type: publication
   url: https://doi.org/10.1093/nar/gks1114
+- type: social media
+  url: http://twitter.com/mypetstore
 ```
 
 #### <a name="parameterObject"></a>Parameter Object