Revert "gkstill's crowd density visuals page no longer exists. Replace it with an archive.org link"

Original website is back online

This reverts commit d4698c998a.

src/App.vue

@@ -17,7 +17,7 @@
 
                     <button @click="$refs.map.reset()" class="rounded absolute right-0 px-2 py-1 text-xs inline-block bg-red-400 shadow-md text-white font-bold hover:shadow-none focus:outline-none">Reset the area</button>
                     <div class="mt-2">
-                        <span class="font-semibold">Crowd density <span class="text-xs text-gray-700"><a class="underline hover:no-underline" target="_blank" href="https://web.archive.org/web/20200903190915/http://www.gkstill.com/Support/crowd-density/625sm/Density6.html">What does it look like?</a></span></span>
+                        <span class="font-semibold">Crowd density <span class="text-xs text-gray-700"><a class="underline hover:no-underline" target="_blank" href="http://www.gkstill.com/Support/crowd-density/625sm/Density6.html">What does it look like?</a></span></span>
                         <input class="block w-full" type="range" min="0.1" max="5.0" step="0.05"  v-model.number="density" />
                     </div>