add get request for hello world

server/src/main/java/com/mixel/docusphere/DocuSphereApplication.java

@@ -2,12 +2,19 @@ package com.mixel.docusphere;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
 
 @SpringBootApplication
+@RestController
 public class DocuSphereApplication {
 
     public static void main(String[] args) {
         SpringApplication.run(DocuSphereApplication.class, args);
     }
 
+    @GetMapping("/hello")
+    public String helloWorld() {
+        return "Hello World!";
+    }
 }