Remove shell from classic-docs deps

- Causing context failures which we could fix
  but shell, afaik, is not needed when creating
  rest docs.

Author: jvalkeal

spring-cloud-dataflow-classic-docs/pom.xml

@@ -34,10 +34,6 @@
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-dataflow-rest-client</artifactId>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.cloud</groupId>
-			<artifactId>spring-cloud-dataflow-shell-core</artifactId>
-		</dependency>
 		<dependency>
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-dataflow-completion</artifactId>