Add timeline javascript to Walkthrough and Examples

[Bojak4616]

Give users the option to see what lies ahead on the left column on the page. It gives a sense of where they are in digesting the information.

Would be easiest to pull out each of the headers and show them on the timeline, highlighting where the user currently is on the page.

Some examples:
https://codyhouse.co/gem/vertical-timeline/
https://codyhouse.co/gem/horizontal-timeline/
https://codepen.io/russelllighthouse/pen/pRXyqW