I gave a link above for a complete power menu - here - alternatively you can use the tutorial from Brink - Power - Add Cascading Desktop Context Menu in Windows 8 but you'll need to add a couple of lines to the reg file for the sleep option:
Also, near the top of the file there is a line that begins:
@="rundll32.exe powrprof.dll,SetSuspendState Sleep"
Add the work 'sleep' between between signout and shutdown.
The reg file is a text file with a .reg extension so you can edit the file with any text editor such as notepad. You can remove your existing entries by using the options from the pages you linked to in your post.