Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
There is no conflict here: this rule expresses that the Subscription must not keel over just because `request` is called synchronously, which is completely independent from allowing that call to possibly be done asynchronously (but properly synchronized). We should also keep in mind that sync/async is not in general related to thread-safety/synchronization, it is only about whether the signaling method is still on the call stack during processing or not.

In any case, this rule is uncontentious.