Adding the stylesheet to the sign-up page

Signed-off-by: Eoghan Conlon <eoghanconlon73@skynet.ie>

src/signup.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8"/>
     <title>Skynet Sign-up</title>
     <link rel="icon" type="image/png" href="images/favicon/favicon-16x16.png"/>
+    <link rel="stylesheet" type="text/css" href="stylesheets/index.css"/>
     <!-- Below to be put refactored into this page's css file upon completion of that branch -->
     <style>
         /* Taken from the W3 schools loader tutorial */