Where is the Extensibility category?

Base on the MS document, I can create an add-in package under "File / New / Project...",

http://msdn.microsoft.com/en-us/library/dn246938.aspx

But I couldn't find the Extensibility category anywhere.  I can see only "Setup and Deployment" and "Visual Studio Solutions" only.

I have existing add-in, which working OK under VS 2012, how can upgrade it to VS 2013?

Thanks,

Steve