docs: remove .catch(t.threw) advice
docs: remove .catch(t.threw) advice

This is no longer necessary.  Unhandled rejections are sent to the
active test's threw() method by the async-hook-domain.

tapjs/node-tap,isaacs/node-tap,evanlucas/node-tap,tapjs/node-tap,isaacs/node-tap,evanlucas/node-tap