Update README to use the default Maven goal

Author: garydgregory

README.md

@@ -86,7 +86,7 @@ There are some guidelines which will make applying PRs easier for us:
 + No tabs! Please use spaces for indentation.
 + Respect the code style.
 + Create minimal diffs - disable on save actions like reformat source code or organize imports. If you feel the source code should be reformatted create a separate PR for this change.
-+ Provide JUnit tests for your changes and make sure your changes don't break any existing tests by running ```mvn clean test```.
++ Provide JUnit tests for your changes and make sure your changes don't break any existing tests by running ```mvn```.
 
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 You can learn more about contributing via GitHub in our [contribution guidelines](CONTRIBUTING.md).