problem: Bitcoin head check may lag because it checks it only once in 15 seconds

solution: use ZeroMQ connection to listen for new blocks

README.adoc

@@ -44,14 +44,8 @@ Blockchains support:
 
 image::dshackle-intro.png[alt="",width=80%,align="center"]
 
-== Roadmap
-
 WARNING: The project is still under development, please use with caution.
 
-- [ ] Subscription to bitcoind notification over gRPC (instead of ZeroMQ)
-- [ ] Lightweight sidecar node connector
-- [ ] Configurable upstream roles
-
 == Quick Start
 
 === Configuration