Documentation edits

Edit the documentation for minor grammar, idiomatic usage, and sentence construction issues.  Overall the documentation is great;  this is just cleaning up some places that sound a little odd.

There are some notes left in the documentation delimited by [bwb: ...] where I made a larger-than-usual change or I thought needed attention from someone more familiar with the codebase than I am.


I think in an old release I chose embed as name for the method. But the method doesn't embed the authenticator only. It saves also the authenticator in the backing store. So I thought init would be a better name because it initializes the authenticator server and client side.