improvements to the login and register pages

This update adds to the instance picker instances for the user to select from, along with some documentation for instance owners on how to add their own instance to the picker

webpage/login.html

@@ -15,7 +15,7 @@
 <form id="form" submit="check(e)">
     <label for="instance"><b>Instance:</b></label><br>
     <p id="verify"></p>
-    <input type="text" placeholder="Instance URL" name="instance" id="instancein" value="https://spacebar.chat/" id="instancein" required><br><br>
+    <input type="search" list="instances" placeholder="Instance URL" name="instance" id="instancein" value="" id="instancein" required><br><br>
 
     <label for="uname"><b>Email:</b></label><br>
     <input type="text" placeholder="Enter email address" name="uname" id="uname" required><br><br>
@@ -31,5 +31,6 @@
 </form>
 <a href="/register.html" id="switch">Don't have an account?</a>
 </div>
+<datalist id="instances"></datalist>
 <script src="/login.js" type="module" ></script>
 </body>