This covers various techniques for using and defining GAsyncResult-style
asynchronous methods, based around the use of examples.

https://bugzilla.gnome.org/show_bug.cgi?id=745092

Thank you aspell.

Also clarify where the commands are supposed to be entered.

- feel less ancient, update to the current app icon style
  & palette

icon-design.page: programatically -> programmatically
menuss.page: targetted -> targeted