[Mezzanine] Sensors user guild for review

I've not even properly proof-read this, but I only just got finished with formatting. I expect to send a final copy to Seeed tomorrow evening for printing. It will be published in booklet form as an A6 sized book.

There are still three graphics missing, but I expect Seeed will get them to me in the next day.

Please review and comment.

Cheers, g.