reorg dir structure:

- keep shared and electron build at root
- move static files for replayweb.page and Jekyll config to docs/
- move Jekyll markdown to docs/docs/

docs/404.html

@@ -0,0 +1,11 @@
+<!doctype html>
+<html class="no-overflow">
+<head>
+</head>
+<body>
+Loading SW, Please wait...
+<script>
+navigator.serviceWorker.register("/swonly.js?replayPrefix=wabac&stats=true", {scope: window.location.origin + "/"}).then(() => window.location.reload());
+</script>
+</body>
+</html>