added admin page

target/classes/templates/index.html

@@ -41,6 +41,8 @@
 		<h1>Registration and Login with Spring Boot, Spring Security,
 			Thymeleaf, Hibernate and MySQL</h1>
 		Welcome <span sec:authentication="principal.username"> User</span>
+		<button type="button" class="btn btn-primary"
+			th:href="@{/admin}">admin</button>
 	</div>
 </body>
 </html>