[Enhancement]: Add example test to the K6 module docs

[FieteO]

Module

K6

Proposal

I am currently trying to setup a k6 integration test and have a hard time figuring out, how tests are supposed to be written with the module.
When googling for solutions, I primarily found an example repository for go and the docs page.
I then looked at the code and found the test case that is provided for the feature:

public class K6ContainerTests {

    @Test
    public void k6StandardTest() throws Exception {
        try (
            // standard_k6 {
            K6Container container = new K6Container("grafana/k6:0.49.0")
                .withTestScript(MountableFile.forClasspathResource("scripts/test.js"))
                .withScriptVar("MY_SCRIPT_VAR", "are cool!")
                .withScriptVar("AN_UNUSED_VAR", "unused")
                .withCmdOptions("--quiet", "--no-usage-report")
            // }
        ) {
            container.start();

            WaitingConsumer consumer = new WaitingConsumer();
            container.followOutput(consumer);

            // Wait for test script results to be collected
            consumer.waitUntil(
                frame -> {
                    return frame.getUtf8String().contains("iteration_duration");
                },
                3,
                TimeUnit.SECONDS
            );

            assertThat(container.getLogs()).contains("k6 tests are cool!");
        }
    }
}

The docs page however, is not stating how a test case would look like and the provided test case does not look like the typical syntax I am used to from testcontainers. I would have expected something similar to the quick start examples to get started quickly.
Either way, I think it would be a good idea to provide an example test in the docs.

(@javaducky @eddumelendez I think you were involved in contributing the module)