Added long missing Migration documentation.
diff --git a/user_guide/nav/nav.js b/user_guide/nav/nav.js
index bc668ec..b9b6e09 100644
--- a/user_guide/nav/nav.js
+++ b/user_guide/nav/nav.js
@@ -103,6 +103,7 @@
'<li><a href="'+base+'libraries/javascript.html">Javascript Class</a></li>' +
'<li><a href="'+base+'libraries/loader.html">Loader Class</a></li>' +
'<li><a href="'+base+'libraries/language.html">Language Class</a></li>' +
+ '<li><a href="'+base+'libraries/migration.html">Migration Class</a></li>' +
'<li><a href="'+base+'libraries/output.html">Output Class</a></li>' +
'<li><a href="'+base+'libraries/pagination.html">Pagination Class</a></li>' +
'<li><a href="'+base+'libraries/security.html">Security Class</a></li>' +