There is some discussion on this here –
https://github.com/kswedberg/jquery-smooth-scroll/issues/27
The solution is simple (no additional plugins required – pls see the end of the post) if you are are ok with change in history for the back button as discussed in the above post.
Steps –
1) Update to the latest version 1.4.13 of the smooth scroll, by downloading the file from
https://github.com/kswedberg/jquery-smooth-scroll/
and replacing the current one placed in js/libs/jquery-smooth-scroll.min.js.
2) Add the option preventDefault: false (default is true which is why the URL does not get updated on click) to the line number 140 in js/main.js file.
That should do as tested by me.