docs(contributing): add note how to execute tests (#600)

Author: mxschmitt

CONTRIBUTING.md

@@ -33,6 +33,10 @@ Names of published driver archives can be found at https://github.com/microsoft/
 ```bash
 mvn compile
 mvn test
+# Executing a single test
+BROWSER=chromium mvn test -Dtest=TestPageNetworkSizes#shouldHaveTheCorrectResponseBodySize
+# Executing a single test class
+BROWSER=chromium mvn test -Dtest=TestPageNetworkSizes
 ```
 
 ### Generating API

pom.xml

@@ -123,6 +123,9 @@
                 junit.jupiter.execution.parallel.config.dynamic.factor=0.5
               </configurationParameters>
             </properties>
+            <failIfNoTests>
+              false
+            </failIfNoTests>
           </configuration>
         </plugin>
         <plugin>