[DOC] Clean up install markdown.
[DOC] Clean up install markdown.

Parkjeahwan/awegeeks,whotooktwarden/gatewayd,xdv/gatewayd,crazyquark/gatewayd,crazyquark/gatewayd,zealord/gatewayd,xdv/gatewayd,Parkjeahwan/awegeeks,zealord/gatewayd,whotooktwarden/gatewayd