Add link to dontkillmyapp.com in the quick start directions

doc/index.html

@@ -40,6 +40,10 @@ manually start it for the first time.
 <li> Optionally run <tt>restorecon -F authorized_keys</tt> (LineageOS
 needs it for "SELinux context").
 <li> Optionally make <tt>.profile</tt>.
+<li> Visit <a href="https://dontkillmyapp.com/">dontkillmyapp.com</a> to
+fix vendor-specific (OnePlus, etc) hacks that break background apps like
+SimpleSSHD.  This website will help you out if SimpleSSHD won't run in
+the background, or won't start after boot, or so on.
 </ul>
 
 <p>If SimpleSSHD does not find an <tt>authorized_keys</tt> file when a