Add a reference to the Spring Boot branch

readme.md

@@ -162,6 +162,11 @@ File -> Import -> Maven -> Existing Maven project
   <tr>
     <th width="300px">Others</th><th width="300px">Files</th>
   </tr>
+    <tr>
+      <td>Spring Boot branch</td>
+      <td>
+        <a href="https://github.com/spring-projects/spring-petclinic/tree/springboot">See here</a></td>
+    </tr>
   <tr>
     <td>Gradle branch</td>
     <td>