Fix inconsistent description about configuration.yml (#289)

CHANGES.md

@@ -18,6 +18,7 @@ Release Notes.
 #### Documentation
 
 * Add a section in `Bootstrap-plugins` doc, introducing HttpURLConnection Plugin compatibility.
+* Update `Plugin automatic test framework` ,fix inconsistent description about configuration.yml
 
 All issues and pull requests are [here](https://github.com/apache/skywalking/milestone/138?closed=1)
 

docs/en/setup/service-agent/java-agent/Plugin-test.md

@@ -58,7 +58,7 @@ All test case codes should be in the `org.apache.skywalking.apm.testcase.*` pack
         |- [resource]
             |- log4j2.xml
     |- pom.xml
-    |- configuration.yaml
+    |- configuration.yml
     |- support-version.list
 
 [] = directory
@@ -79,7 +79,7 @@ All test case codes should be in the `org.apache.skywalking.apm.testcase.*` pack
             |- [WEB-INF]
                 |- web.xml
     |- pom.xml
-    |- configuration.yaml
+    |- configuration.yml
     |- support-version.list
 
 [] = directory