fix typo: Loged -> Logged

The past participle of "to log in" is "logged in".
See <https://www.wordhippo.com/what-is/the-past-tense-of/log_in.html>

src/App.js

@@ -128,7 +128,7 @@ class App extends React.Component {
     this.storeState("", "", "");
   }
 
-  isLoged() {
+  isLoggedIn() {
     if (!this.state.token) {
       return false;
     }
@@ -161,7 +161,7 @@ class App extends React.Component {
 
   render() {
     let component;
-    if (!this.isLoged()) {
+    if (!this.isLoggedIn()) {
       component = <SignIn onLogin={this.login} />;
     } else {
       component = <Panel onLogout={this.logout} />;