Fix broken autoload for magit-dispatch-popup

[jgkamat]

I'm not sure if this will fix it, but it seems like it will.

I pulled from the documentation, and this example autload for the same type of macro.

From the documentation

If you write a function definition with an unusual macro that is not one of the known and recognized function definition methods, use of an ordinary magic autoload comment would copy the whole definition into loaddefs.el. That is not desirable. You can put the desired autoload call into loaddefs.el instead by writing this:

 ;;;###autoload (autoload 'foo "myfile")
 (mydefunmacro foo
   ...)

Closes #161

[stardiviner]

Please bump version so that MELPA can pull down.

[vermiculus]

@stardiviner I really only try to tag stable versions. Consider switching to normal MELPA or putting the autoload form in your own config.

[stardiviner]

@vermiculus You're right. Thanks.