Polishing

Make the master branch CI status badge explicitly point to the master branch of CircleCI.

Author: gregturn

README.adoc

@@ -1,6 +1,6 @@
 = Spring Web Services
 
-image:https://circleci.com/gh/spring-projects/spring-ws.svg?style=svg["CircleCI", link="https://circleci.com/gh/spring-projects/spring-ws"]
+image:https://circleci.com/gh/spring-projects/spring-ws/tree/master.svg?style=svg["CircleCI", link="https://circleci.com/gh/spring-projects/spring-ws/tree/master"]
 
 Spring Web Services is a product of the Spring community focused on creating
 document-driven Web services. Spring Web Services aims to facilitate