wireless-wpa and netctl.profile.5.txt clearification

Adjusted "Key=" definition in netctl.profile(5) and cleaned up some of the colors. Found some *mandatory* and others not. Anything *mandatory* has the effect to help emphasis it's requirement(s). 

Clarified doc/example/wireless-wpa  added three explanations along with three examples of how "Key=" can be set. I did not reference the man page in the example document since I believe it should go without saying that the manuals should be read before attempting to configure a tool for the first time in order to ensure you're using it properly.