Update ICS instructions

www/icsGenerator/index.html

@@ -64,6 +64,18 @@
 					<li>Done!  You can now view the event in your calendar</li>
 				</ol>
 			</p>
+			<p>
+				<h2>Mozilla Thunderbird:</h2>
+				<ol>
+					<li>Press Alt</li>
+					<li>Click on File</li>
+					<li>Hover on Open</li>
+					<li>Click on Calendar File...</li>
+					<li>Locate the ICS you just downloaded (if you didn't save it, click the link again and save it)</li>
+					<li>Click Open</li>
+					<li>Done!  You can now view the event in your calendar</li>
+				</ol>
+			</p>
 		</div>
 		<script>
 			if (window.location.search) {