src/404.htm: Update page

This is a bit less abrasive and a tad bit more helpful.  As I've mentioned
in previous commits, the goal of this site has since changed.

src/404.htm

@@ -1,20 +1,28 @@
 <article>
-  <h1>Page Not Found</h1>
+  <h1>Page Not Found (404)</h1>
 
   <p>
-    Sorry&nbsp;the page you requested cannot be found; it may have been removed
-    or you may have stumbled across a broken link. If you believe that you
-    have received this message in error, please contact Mike directly. If
-    you have arrived at this page from an external link, please contact the
-    author of that website instead.
+    The page you requested cannot be found&mdash;it may have been removed
+      or you may have stumbled across a broken link.
+    If you manually entered the URL,
+      please verify that it was entered correctly.
+    If you believe that you have received this message in error,
+      please contact
+      <a href="mailto:404@mkegerwitz.com">404@mikegerwitz.com</a>
+      with the full URL of this page.
+
   </p>
-
   <p>
-    [This is where one would insert the obligatory &ldquo;we apologize for the
-    inconvenience&rdquo;...but this is a personal site, not a business, so I'm not all
-    that sympathetic. If it's a bug, it'll be fixed. If you think that the page
-    you're looking for should exist (and that it did in the past), consider looking
-    through this site's repository (available on the Projects page) and seeing what
-    might have happened to it. Good day to you, kind sir/madam/otherwise.]
+    You may also check
+    <a id="ia" href="https://web.archive.org/https://mikegerwitz.com/">The Internet
+    Archive</a> for this page.
   </p>
 </article>
+
+<!-- try to be helpful, if scripts are enabled -->
+<script>
+  // @license magnet:?xt=urn:btih:1f739d935676111cfff4b4693e3816e664797050&dn=gpl-3.0.txt GPL-v3-or-Later
+  document.getElementById( 'ia' ).href =
+    'https://web.archive.org/' + document.location.href;
+  // @license-end
+</script>