Added some notes on concurrency/parallelism

README.md

@@ -7,4 +7,9 @@ Currently, most of the code is just a copy of the excellent cron package
 found in the BuildBox package (http://hackage.haskell.org/package/BuildBox)
 by Ben Lippmeier, slightly adjusted to execute arbitrary IO () actions.
 
+Currently, no parallelism/concurrency is involved at all, the scheduler just
+runs jobs and blocks while doing so. Adding support for these is one of the
+major goals for the future. Nevertheless, you can run the whole scheduler
+as some kind of worker by just forking it off using forkIO/forkOS.
+
 License: BSD3, see LICENSE