Remove signout option and import NavDropdown in Header.js

src/App.js

@@ -40,7 +40,7 @@ function App() {
     { label: "Home", link: "/" },
     { label: "About", link: "/about" },
     { label: "Contact", link: "/contact" },
-    { label: "Log out", link: "/signout" }
+  
   ]
 
   /// application states

src/components/Header.js

@@ -1,6 +1,7 @@
 import Container from "react-bootstrap/Container"
 import Navbar from "react-bootstrap/Navbar"
 import Nav from "react-bootstrap/Nav"
+import { NavDropdown } from "react-bootstrap/NavDropdown"
 
 export function Header ( props ) {
     // props.items is the value of nav state in App.js