Remove grunt-build-atom-shell

That thing is deprecated for _sure_

docs/tutorial/application-distribution.md

@@ -109,6 +109,7 @@ You can rename the `electron` executable to any name you like.
 Apart from packaging your app manually, you can also choose to use third party
 packaging tools to do the work for you:
 
+* [electron-forge](https://github.com/electron-userland/electron-forge)
 * [electron-builder](https://github.com/electron-userland/electron-builder)
 * [electron-packager](https://github.com/electron-userland/electron-packager)
 
@@ -118,21 +119,11 @@ It is also possible to rebrand Electron by changing the product name and
 building it from source. To do this you need to modify the `atom.gyp` file and
 have a clean rebuild.
 
-### grunt-build-atom-shell
-
-Manually checking out Electron's code and rebuilding could be complicated, so
-a Grunt task has been created that will handle this automatically:
-[grunt-build-atom-shell](https://github.com/paulcbetts/grunt-build-atom-shell).
-
-This task will automatically handle editing the `.gyp` file, building from
-source, then rebuilding your app's native Node modules to match the new
-executable name.
-
 ### Creating a Custom Electron Fork
 
 Creating a custom fork of Electron is almost certainly not something you will
 need to do in order to build your app, even for "Production Level" applications.
-Using a tool such as `electron-packager` or `electron-builder` will allow you to
+Using a tool such as `electron-packager` or `electron-forge` will allow you to
 "Rebrand" Electron without having to do these steps.
 
 You need to fork Electron when you have custom C++ code that you have patched