Mention Spago as a recommended build tool

[LiamGoodacre]

Currently the website mentions:

The recommended build tool for beginners is Pulp, which can be installed using npm:
npm install -g pulp bower

I think it'd be useful to first mention spago, then pulp & bower as an alternative.

Thoughts?

[hdgarrood]

I agree, but I think we should make sure the documentation repo agrees - if I remember correctly there’s a getting started guide in there which ideally would be updated at the same time

[hdgarrood]

This was resolved by #138