Modernizing the docs pom (spring-cloud#345)

I tossed out dependencies we don't need once we start using spring-doc-resources.

NOTE: This PR depends on spring-cloud/spring-cloud-build#84

Author: Buzzardo

docs/pom.xml

@@ -49,6 +49,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-antrun-plugin</artifactId>
+						<inherited>false</inherited>
 					</plugin>
 				</plugins>
 			</build>