Add canonical link to index.html

Author: RaspberryPi400

index.html

@@ -7,6 +7,7 @@
   <meta name="title" content="Study Guide Creator">
   <meta name="description" content="This website helps you create study guides and test yourself. You input the questions & answers, then take the test and get an instant score."/>
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <link rel="canonical" href="https://raspberrypi400.github.io/study/"/>
   <link rel="icon" type="image/x-icon" href="favicon.ico">
   <link rel="stylesheet" href="style1.css">
 </head>