Update README.md to include javadoc.io

Note: the doc version is older because maven central hasn't been updated with the current releases.

README.md

@@ -7,6 +7,8 @@ Reaper for Apache Cassandra
 
 [![Hosted By: Cloudsmith](https://img.shields.io/badge/OSS%20hosting%20by-cloudsmith-blue?logo=cloudsmith&style=flat-square)](https://cloudsmith.io/~thelastpickle/repos/reaper/packages/)
 
+[![javadoc](https://javadoc.io/badge2/io.cassandrareaper/cassandra-reaper/javadoc.svg)](https://javadoc.io/doc/io.cassandrareaper/cassandra-reaper)
+
 Reaper is a centralized, stateful, and highly configurable tool for running Apache Cassandra repairs against single or multi-site clusters.
 
 The current version supports running Apache Cassandra cluster repairs in a segmented manner,  opportunistically running multiple parallel repairs at the same time on different nodes within the cluster. Basic repair scheduling functionality is also supported.
@@ -54,4 +56,4 @@ Dependencies
 
 Reaper uses an unmodified EPL-2.0 licensed dependency: [EclipseStore](https://eclipsestore.io/). The source code can be found in the [GitHub repository](https://github.com/eclipse-store/store).
 
-*Note: This repo is a fork from the original Reaper project, created by the awesome folks at Spotify.*
+*Note: This repo is a fork from the original Reaper project, created by the awesome folks at Spotify.*