[REVIEW][Java] Add instructions on how to run a single test (#1004)

This PR adds some lines to the Java specific readme, explaining how to run a single test/a single test suite (useful in case of debugging or error reproduction).

Authors:
  - Lorenzo Dematté (https://github.com/ldematte)
  - Corey J. Nolet (https://github.com/cjnolet)

Approvers:
  - MithunR (https://github.com/mythrocks)
  - Corey J. Nolet (https://github.com/cjnolet)

URL: #1004

Author: ldematte

java/README.md

@@ -25,6 +25,18 @@ do `./build.sh java` in the top level directory or just do `./build.sh` in this
 
 Run `./build.sh --run-java-tests` from this directory.
 
+To run a single test:
+```sh
+cd cuvs-java/
+mvn verify -Dintegration-test=com.nvidia.cuvs.CagraBuildAndSearchIT
+```
+Be sure to set (manually, if needed) your `LD_LIBRARY_PATH` to include the directory with the appropriate (matching)
+version of `libcuvs.so`.
+Also, ensure that your panama bindings are up-to-date. They can be re-generated by running:
+```sh
+./panama-bindings/generate-bindings.sh
+```
+
 
 ## Examples