Add a new requirement to the Managing mongocryptd section of the client-side encryption specification for drivers to ensure that stdout/stderr of mongocryptd auto-started processes are redirected to /dev/null (or on Windows, NUL)

The lack of this can cause a deadlock, because mongocryptd flushes its log synchronously with handling of socket responses. If the owner of the stdout/err streams (in this case the driver) is not pulling data off of these streams, mongocryptd will block trying to flush the streams.