Draft GitHub Releases transport mechanism

Author: probonopd

draft.md

@@ -196,6 +196,24 @@ zsync file URL | String | `http://server.domain/path/Application-latest-x86_64.A
 
 For an overview about [zsync] and how to create `.zsync` files, see [http://zsync.moria.org.uk/](http://zsync.moria.org.uk/).
 
+##### GitHub Releases
+
+The __GitHub Releases__ transport extends the [zsync] transport in that it uses version information from [GitHub Releases](https://help.github.com/articles/about-releases/). Its [update information] is in the form
+
+```
+gh-zsync|probono|AppImages|latest|Subsurface-*-x86_64.AppImage.zsync
+```
+
+If an [AppImage] has [update information] embedded for this transport mechanism, then the following fields **MUST** be used; separated by a "|" character:
+
+Field | Type | Example | Comments
+----------- | ------ | -------- | --------
+Transport mechanism | String | `gh-zsync` | [zsync] file and [AppImage] **MUST** be stored on GitHub Releases
+Bintray username | String | `probono` | Name of the GitHub user or organization of the account where the [zsync] file and [AppImage] are stored
+Bintray repository | String | `AppImages` | Name of the GitHub repository in which the [zsync] file and [AppImage] are stored
+Release name | String | `latest` | Name of the release. `latest` will automatically use the latest release as determined by the GitHub API
+Filename | String | `Subsurface-*-x86_64.AppImage.zsync` | Filename of the [zsync] file on GitHub, `*` is a wildcard
+
 ##### bintray-zsync
 
 The __bintray-zsync__ transport extends the [zsync] transport in that it uses version information from [Bintray](http://bintray.com/). Its [update information] is in the form