mention that Trust triggers reload

IPython/html/static/notebook/js/notebook.js

@@ -1820,6 +1820,8 @@ var IPython = (function (IPython) {
                         $("<em>").text("when you open it")
                     )
                 ).append(".")
+            ).append($("<p>")
+                .text("Selecting trust will immediately reload this notebook in a trusted state.")
             ).append($("<p>")
                 .text("For more information, see the ")
                 .append($("<a>").attr("href", "http://ipython.org/security.html")