Misc. README updates (#33)

* Reference data-digger in README

* Remove redundant roadmap info from readme

* Update README

README.md

@@ -23,6 +23,11 @@ non-Kafka-related contexts.
 See [this blog post](https://segment.com/blog/easier-management-of-Kafka-topics-with-topicctl/) for
 more details.
 
+## Related projects
+
+Check out the [data-digger](https://github.com/segmentio/data-digger) for a command-line tool
+that makes it easy to tail and summarize structured data in Kafka.
+
 ## Roadmap
 
 We are planning on making some changes to (optionally) remove the ZK dependency and also to support
@@ -386,20 +391,7 @@ the following depend on broker APIs:
 5. `apply` with topic creation
 
 In the future, we may shift more functionality away from ZooKeeper, at least for newer cluster
-versions; see the "Feature roadmap" section below for more details.
-
-## Feature roadmap
-
-The following are in the medium-term roadmap:
-
-1. **Use broker APIs exclusively for newer cluster versions:** This is needed for a
-  [future world](https://www.confluent.io/blog/removing-zookeeper-dependency-in-kafka/)
-  where Kafka doesn't use ZooKeeper at all. Even before that happens, though, doing everything
-  through broker APIs simplifies the configuration and is also needed to run `topicctl` in
-  environments where users aren't given direct ZK access.
-2. **Support TLS for communication with cluster:** This is fairly straightforward assuming
-  that (1) is done. It allows `topicctl` to be run in environments that don't permit insecure
-  cluster access.
+versions; see the "Roadmap" section above for more details.
 
 ## Development