Update doc header/footer

Update the documentation header and footer to be consistent with the MIT
App Inventor website.

Change-Id: I90b630fd122a35e9b36662ad3bf15d2dc876f55c

appinventor/docs/markdown/_includes/footer.html

@@ -12,16 +12,16 @@
 	<div class="col-xl-6 legal text-center">
 	    <ul>
 		<li>
-		    <a href="http://creativecommons.org/licenses/by-sa/3.0/"
-                       target="_blank" class="btn btn-link" role="button">This work is licensed under a Creative Commons Attribution-ShareAlike 3.0</a>
+		    <a href="http://web.mit.edu" class="btn btn-link" role="button"
+                       target="_blank">© 2012-2020 Massachusetts Institute of Technology</a>
 		</li>
 		<li>
 		    <a href="http://creativecommons.org/licenses/by-sa/3.0/"
-                       target="_blank" class="btn btn-link" role="button">Unported License Terms of Service</a>
+                       target="_blank" class="btn btn-link" role="button">This work is licensed under a Creative Commons Attribution-ShareAlike 3.0</a>
 		</li>
 		<li>
-		    <a href="http://web.mit.edu" class="btn btn-link" role="button"
-                       target="_blank">© 2012-2019 Massachusetts Institute of Technology</a>
+		    <a href="http://appinventor.mit.edu/about/termsofservice"
+                       target="_blank" class="btn btn-link" role="button">Terms of Service and Privacy Policy</a>
 		</li>
 	    </ul>
 	</div>

appinventor/docs/markdown/_includes/header.html

@@ -20,6 +20,7 @@
 		    <a class="dropdown-item" href="http://appinventor.mit.edu/explore/app-month-gallery">App of the Month</a>
                     <a class="dropdown-item"
                        href="http://appinventor.mit.edu/ai2/ReleaseNotes">Release Notes</a>
+                    <a class="dropdown-item" href="http://appinventor.mit.edu/about/termsofservice" target="_blank">Terms of Service</a>
 		</div>
 	    </li>
 	    <li class="nav-item dropdown">
@@ -57,6 +58,7 @@
                        target="_blank">Open Source Information</a>
 	            <a class="dropdown-item" href="http://appinventor.mit.edu/explore/research">Research</a>
                     <a class="dropdown-item" href="http://appinventor.mit.edu/explore/hour-of-code">Hour of Code</a>
+                    <a class="dropdown-item" href="http://appinventor.mit.edu/explore/resources">Additional Resources</a>
 		</div>
 	    </li>
             <li class="nav-item dropdown">