scp: Document more scp functionts.
scp: Document more scp functionts.

nviennot/libssh,sebadoom/libssh,wangshawn/libssh,mwgoldsmith/libssh,wangshawn/libssh,DouglasHeriot/libssh,kedazo/libssh,DouglasHeriot/libssh,bigcat26/libssh-mod,elastichosts/libssh,taikoo/libssh,elastichosts/libssh,Distrotech/libssh,robxu9/libssh,nviennot/libssh,sebadoom/libssh,wangshawn/libssh,pouete/libssh,Distrotech/libssh,robxu9/libssh,sebadoom/libssh,mwgoldsmith/ssh,nviennot/libssh,sebadoom/libssh,taikoo/libssh,kedazo/libssh,pouete/libssh,Distrotech/libssh,mwgoldsmith/libssh,bigcat26/libssh-mod,pouete/libssh,DouglasHeriot/libssh,mwgoldsmith/ssh,kedazo/libssh,robxu9/libssh,mwgoldsmith/ssh,kedazo/libssh,taikoo/libssh,robxu9/libssh,nviennot/libssh,elastichosts/libssh,pouete/libssh,mwgoldsmith/ssh,bigcat26/libssh-mod,bigcat26/libssh-mod,mwgoldsmith/libssh,wangshawn/libssh,mwgoldsmith/libssh,taikoo/libssh,Distrotech/libssh,DouglasHeriot/libssh