* Make syncShutdown unavailable from async
Motivation
syncShutdown can cause unbounded thread blocking, we shouldn't allow it
in concurrent code.
Modification
Mark syncShutdown unavailable from async.
Result
Users are warned if they try to syncShutdown in an async context
* Only noasync on 5.7
Motivation
Documentation is nice, and we can help support users by providing useful
clear docs.
Modifications
Add Docc to 5.6 and later builds
Make sure symbol references work
Add overview docs
Result
Nice rendering docs