Update settings.py to correct a few things, whatads.html to tell admins what to do, why.html to correct the spelling, layout.html to update the embed description, remove sign from templates, update README.foreskin to reflect recent changes and update README.md to have more instructions

Whew, that was a lot of stuff.

closedverse_main/templates/closedverse_main/help/whatads.html

@@ -12,6 +12,8 @@
         <p>These ads shows up in activity, user pages, homepage, and more.</p>
         <h2>How can I have my user-generated ad?</h2>
 	<p>Contact an admin.</p>
+	<h2>I am an admin.</h2>
+	<p>Go to the admin panel, and go to the ads section. If you can't see it, you don't have permissions to view ads.</p>
       </div>
     </div>
   </div>