Change shortcut to `n`.

app/assets/javascripts/shortcuts.js

@@ -25,7 +25,7 @@
         }
       }
 
-      Mousetrap.bind('m', function() {
+      Mousetrap.bind('n', function() {
         $('.global-dropdown-menu').addClass('shortcuts')
         $('.global-dropdown-toggle').trigger('click');
       });

app/views/help/_shortcuts.html.haml

@@ -17,8 +17,8 @@
                   %th Global Shortcuts
                 %tr
                   %td.shortcut
-                    .key m
-                  %td Main Menu
+                    .key n
+                  %td Main Navigation
                 %tr
                   %td.shortcut
                     .key s