refactor: move first Spring Boot app to com.krishna.firstspringbootap…

…p package

src/main/java/com/krishna/Main.java → src/main/java/com/krishna/firstspringbootapp/Main.java

@@ -1,4 +1,4 @@
-package com.krishna;
+package com.krishna.firstspringbootapp;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;