update restdocs, move to spring-5

spring-5/src/main/java/com/baeldung/restdocs/IndexController.java

@@ -0,0 +1,21 @@
+package com.baeldung.restdocs;
+
+import static org.springframework.hateoas.mvc.ControllerLinkBuilder.linkTo;
+
+import org.springframework.hateoas.ResourceSupport;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/")
+public class IndexController {
+
+    @GetMapping
+    public ResourceSupport index() {
+        ResourceSupport index = new ResourceSupport();
+        index.add(linkTo(CRUDController.class).withRel("crud"));
+        return index;
+    }
+
+}