Fix an incorrect types deprecation message.

server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestGetFieldMappingAction.java

@@ -49,7 +49,7 @@ public class RestGetFieldMappingAction extends BaseRestHandler {
     private static final DeprecationLogger deprecationLogger = new DeprecationLogger(
         LogManager.getLogger(RestGetFieldMappingAction.class));
     static final String TYPES_DEPRECATION_MESSAGE = "[types removal] The parameter include_type_name " +
-        "should be explicitly specified in get index requests to prepare for 7.0. In 7.0 include_type_name " +
+        "should be explicitly specified in get field mapping requests to prepare for 7.0. In 7.0 include_type_name " +
         "will default to 'false', which means responses will omit the type name in mapping definitions.";
 
     public RestGetFieldMappingAction(Settings settings, RestController controller) {