Add changelog for Follow entity

CHANGELOG.md

@@ -7,6 +7,8 @@
 
 ### Added
 * New style Diaspora public payloads are now supported (see [here](https://github.com/diaspora/diaspora_federation/issues/30)). Old style payloads are still supported. Payloads are also still sent out old style.
+* Add new `Follow` base entity and support for the new Diaspora "contact" payload. The simple `Follow` maps to Diaspora contact entity with following/sharing both true or false. Sharing as a separate concept is not currently supported.
+
 
 ## [0.11.0] - 2017-05-08