Point to https://github.com/AppImage/AppImageSpec

Author: probonopd

README.md

@@ -12,7 +12,7 @@ conveniently handling AppImages.
 
 https://en.wikipedia.org/wiki/AppImage
 
-This document describes the AppImage format and AppImageKit. It is intended to describe the philosophy behind the AppImage format and the concrete implementation. This document is not a formal specification, since the AppImage format is not frozen yet but in the process of being specified more formally. Contributors are encouraged to comment on this document and propose formal format descriptions.
+This document describes the AppImage format and AppImageKit. It is intended to describe the philosophy behind the AppImage format and the concrete implementation. This document is not a formal specification, since the AppImage format is not frozen yet but in the process of being specified more formally at https://github.com/AppImage/AppImageSpec. Contributors are encouraged to comment.
 
 Significant upstream projects have started providing AppImages of releases and/or nightly/continuous builds, see this [list of upstream-provided AppImages](https://github.com/probonopd/AppImageKit/wiki/AppImages#upstream-appimages).