[MERGE] tortoise-strategy document

[Alexander Belchenko]

Mark Hammond пишет:
> As threatened last week, I've attached a merge request for the tortoise
> document - I hope I've put it together correctly.  This is the same version
> as previously sent, except all of the typos identified by Alexander have
> been fixed.
> 
> There is still plenty of time left for feedback, but otherwise there are no
> other changes I have planned - so the sooner the feedback comes, the better!

BundleBuggy did not catch this merge request so you could resubmit it. Anyway
bb:approve from me.