Added some basic documentation about running these JMH tests

Author: orpiske

README.md

@@ -1,3 +1,19 @@
 # Apache Camel Performance Tests
 
 This project provides performance tests for Apache Camel.
+
+## Running the Performance Tests
+
+### Camel JMH
+
+The performance tests located in the `camel-jmh` module can be run using the following command:
+
+```bash
+mvn -l camel-${version}-jmh-test.log -DargLine="-XX:+UseNUMA -Xmx4G -Xms4G -server" -Dcamel.version=${version} -Pjmh -Dtest=${TESTS}  clean test
+```
+
+Where:
+* `${version}` is the Apache Camel version to use.
+* `${TESTS}` is a comma-separated list of tests to run (e.g., `AggregatorTest,ContentBasedRouterBodyTest`).
+
+After running the tests, the results are stored in JMH JSON files (i.e.: `<test name>.jmh.json`).