format reference doc

spring-cloud-alibaba-docs/src/main/asciidoc/dependency-management.adoc

@@ -6,6 +6,8 @@ Version 0.2.1.RELEASE is compatible with the Spring Cloud Finchley. Version 0.1.
 
 These artifacts are available from Maven Central and Spring Release repository via BOM:
 
+[source,xml]
+----
 <dependencyManagement>
     <dependencies>
         <dependency>
@@ -17,10 +19,12 @@ These artifacts are available from Maven Central and Spring Release repository v
         </dependency>
     </dependencies>
 </dependencyManagement>
-add the module in dependencies.
+----
 
 If you want to use the latest BUILD-SNAPSHOT version, add Spring Snapshot Repository in pom.xml , Attention: BUILD-SNAPSHOT may be updated in any time
 
+[source,xml]
+----
 <repositories>
     <repository>
         <id>spring-snapshot</id>
@@ -31,3 +35,4 @@ If you want to use the latest BUILD-SNAPSHOT version, add Spring Snapshot Reposi
         </snapshots>
     </repository>
 </repositories>
+----