added links to java readme

Author: Heliozoa

plugins/java/README.md

@@ -4,6 +4,17 @@ This crate differs from the others in that it contains two different plugins wit
 
 The `./deps` directory contains some Java dependencies, such as a bundled Maven for use by the Maven plugin.
 
+- Maven: https://maven.apache.org/download.cgi
+- j4rs: https://github.com/astonbitecode/j4rs/releases
+- tmc-checkstyle-runner:
+  - https://github.com/testmycode/tmc-checkstyle-runner/blob/master/pom.xml
+  - https://maven.mooc.fi/snapshots/fi/helsinki/cs/tmc/tmc-checkstyle-runner/3.0.3-SNAPSHOT/maven-metadata.xml
+  - https://maven.mooc.fi/snapshots/fi/helsinki/cs/tmc/tmc-checkstyle-runner/3.0.3-SNAPSHOT/tmc-checkstyle-runner-3.0.3-20200520.064542-3.jar
+- tmc-junit-runner:
+  - https://github.com/testmycode/tmc-junit-runner/blob/master/pom.xml
+  - https://maven.mooc.fi/snapshots/fi/helsinki/cs/tmc/tmc-junit-runner/0.2.9-SNAPSHOT/maven-metadata.xml
+  - https://maven.mooc.fi/snapshots/fi/helsinki/cs/tmc/tmc-junit-runner/0.2.9-SNAPSHOT/tmc-junit-runner-0.2.9-20200609.211712-1.jar
+
 ## Maven
 
 ### Student file policy