updated message that helps run properly ConfigurationExporterTest on …

…windows (#3449)

CONTRIBUTING.md

@@ -265,8 +265,9 @@ See [`apm-agent-plugins/README.md`](apm-agent-plugins/README.md)
 
 HTML Documentation is generated from text files stored in `docs` folder using [AsciiDoc](http://asciidoc.org/) format.
 The `configuration.asciidoc` file is generated from running `co.elastic.apm.agent.configuration.ConfigurationExporter`
-(e.g. via `./mvnw -Dsurefire.failIfNoTests=false -Dtest=ConfigurationExporterTest -pl apm-agent -am clean test`). All the other asciidoc text files
-are written manually.
+(e.g. via `./mvnw -Dsurefire.failIfNoTests=false -Dtest=ConfigurationExporterTest -pl apm-agent -am clean test`
+or on Windows `.\mvnw "-Dsurefire.failIfNoTests=false" "-Dsurefire.failIfNoSpecifiedTests=false" -Dtest=ConfigurationExporterTest -pl apm-agent-builds/apm-agent -am clean test`). 
+All the other asciidoc text files are written manually.
 
 A preview of the documentation is generated for each pull-request.
 Click on the build `Details` of the `elasticsearch-ci/docs` job and go to the bottom of the `Console Output` to see the link.

apm-agent-builds/apm-agent/src/test/java/co/elastic/apm/agent/configuration/ConfigurationExporterTest.java

@@ -120,7 +120,8 @@ void testGeneratedConfigurationDocsAreUpToDate() throws IOException, TemplateExc
         assertThat(renderedDocumentation)
             .withFailMessage("The rendered configuration documentation (/docs/configuration.asciidoc) is not up-to-date.\n" +
                 "If you see this error on CI, it means you have to execute the tests locally " +
-                "(./mvnw -Dsurefire.failIfNoTests=false -Dtest=ConfigurationExporterTest -pl apm-agent -am clean test) " +
+                "(./mvnw -Dsurefire.failIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false -Dtest=ConfigurationExporterTest -pl apm-agent -am clean test) " +
+                "or on Windows(.\\mvnw \"-Dsurefire.failIfNoTests=false\" \"-Dsurefire.failIfNoSpecifiedTests=false\" -Dtest=ConfigurationExporterTest -pl apm-agent-builds/apm-agent -am clean test) " +
                 "which will update the rendered docs.\n" +
                 "If you see this error while running the tests locally, there's nothing more to do - the rendered docs have been updated " +
                 "and the following test execution should not have failed.")