Added "Installing flash player on firefox" section to QuickStart

[Siju George]

Hi,

This is nothing but Chris's howto refined. Hope it is ok?

http://www.dragonflybsd.org/docs/newhandbook/environmentquickstart/?updated#index5h2

I am running 2.9 with dragonfly-2010Q3. But the same worked for me in 2.8
too with Q2.

thanks

--Siju