[TestNG] Add README.md with usage instructions

testng/README.md

@@ -0,0 +1,43 @@
+Cucumber TestNG 
+==============
+
+Use TestNG to execute cucumber scenarios.
+
+Add the `cucumber-testng` dependency to your pom.
+
+```xml
+<dependencies>
+  [...]
+    <dependency>
+        <groupId>io.cucumber</groupId>
+        <artifactId>cucumber-testng</artifactId>
+        <version>${cucumber.version}</version>
+        <scope>test</scope>
+    </dependency>
+  [...]
+</dependencies>
+```
+
+Create an empty class that extends the `AbstractTestNGCucumberTests`.
+
+```java
+package cucumber.runtime.testng;
+
+import cucumber.api.CucumberOptions;
+import cucumber.api.testng.AbstractTestNGCucumberTests;
+
+@CucumberOptions(plugin = "json:target/cucumber-report.json")
+public class RunCukesTest extends AbstractTestNGCucumberTests {
+}
+```
+
+This will execute all scenarios in same package as the runner, by default glue code is also assumed to be in the same 
+package. The `@CucumberOptions` can be used to provide
+[additional configuration](https://cucumber.io/docs/reference/jvm#list-configuration-options) to the runner. 
+
+
+## Test composition ##
+
+It is possible to use TestNG without inheriting from `AbstractTestNGCucumberTests` by using the `TestNGCucumberRunner`. 
+See the [RunCukesByCompositionTest Example](../examples/java-calculator-testng/src/test/java/cucumber/examples/java/calculator/RunCukesByCompositionTest.java) 
+for usage.