EventWriter: Document / decide what to do about blocking write operations

[stephen-fox]

While working on a project that uses this library, I implemented an Encoder that (accidentally) produced a deadlock. While write operations are usually considered non-blocking operations, there are exceptions such as writing to a FIFO pipe (by default the write blocks until a read occurs).

In discussing the issue with @JAORMX, Ozz felt we should either support cancellation or document such a cases in the auditevent library.