add link to architecture.html from main page

h2/src/docsrc/html/fragments.html

@@ -95,6 +95,7 @@ translate -->
 <a href="links.html">Links</a><br />
 <a href="jaqu.html">JaQu</a><br />
 <a href="mvstore.html">MVStore</a><br />
+<a href="architecture.html">Architecture</a><br />
 <br />
 
 </div>