Tooltip formatter in a Doc example

[steven-pribilinskiy]

At this doc page that code is not functioning:

            tooltip: {
                y: {
                    title: {
                        formatter: function (val) {
                            if (val === 'Session Duration') return val + " (mins)"
                            else if (val === 'Page Views') return val + " per session"
                            return val;
                        }
                    }
                }
            },

[junedchhipa]

Fixed the code - the website page will also be updated soon