[site/home][s]: get home page subscription form working (hopefully!).

* Forms were not working on netlify prob because hydration was removing the hidden form tag so added explicitly - see https://answers.netlify.com/t/forms-not-being-sent-with-next-js/15602/4
* Add /subscribed page where people are redirected

site/components/Home/Hero.js

@@ -25,6 +25,7 @@ export function Hero() {
                         placeholder="Enter your email"
                         className="block w-full px-4 py-3 rounded-md border-0 text-base text-gray-900 placeholder-gray-500 focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-indigo-300 focus:ring-offset-gray-900"
                       />
+                      <input type="hidden" name="form-name" value="get-updates" />
                     </div>
                     <div className="mt-3 sm:mt-0 sm:ml-3">
                       <button

site/pages/subscribed.md

@@ -0,0 +1,5 @@
+# Thanks for subscribing for updates
+
+Thanks for subscribing. You will start getting our regular updates soon.
+
+If at any time you need to unsubscribe instructions will be in the emails.