Update evangelistmanifesto.asciidoc
Other terms
Add in Andy's suggested term
Add in Twitter terms

From https://dev.twitter.com/developer-advocate
Merge pull request #4 from chrisalexander/patch-2

Going to edit the title of the section a bit but I will add it. But to be clear
This is developer evangelists or developer advocates - not the non-developer types
Merge pull request #3 from chrisalexander/patch-1

Evangelists work internally too. Really like this one - thanks!
updates based on the merged git changes
added new link