Install documentation clarification for Windows

[mattlaver]

The document states:

"Checkout Manos from github at http://github.com/jacksonh/manos/ and build/install it using Visual Studio"

However for clarity, I think it would be good to state that you need to use Visual Studio 2010 or greater as the project uses .Net 4.0 features (like default parameters).

So I would tweak it to something like:

"Checkout Manos from github at http://github.com/jacksonh/manos/ and build/install it using Visual Studio 2010 or greater"

Would also be nice to have install instructions for people that don't use Visual Studio.