Merge branch 'readme-plugins' into 'nightly'

Readme plugins

* Adds several plugin READMEs
  They are pretty basic, but it's a start.

* Changes status.net/wiki URLs to git.gnu.io
  The status.net wiki is dead.

See merge request !103

plugins/Favorite/README

@@ -0,0 +1,11 @@
+The Favorite plugin adds the ability to mark a notice as a "favorite"
+(i.e. "like").
+
+Installation
+============
+This plugin is enabled by default
+
+Settings
+========
+none
+