fix wording

WEBROOT/login.php

@@ -156,7 +156,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
             <form method="post">
                 <input type="text" name="username" placeholder="Benutzername" required>
                 <input type="password" name="password" placeholder="Passwort" required>
-                <button type="submit">Login</button>
+                <button type="submit">Einloggen</button>
             </form>
 
             <button style="margin-top: 9px" type="button"