Add drop-down for article headers

[sps1112]

Problem:- The articles can sometimes be very long and difficult to read in a single sitting.

Issue with Problem:- Makes people drop off and becomes less likely they will come back and read the article till the end.

Current Solution (if any):- Dropdowns for headings can be included in the articles such as on Wikipedia and other .wiki websites.

Task:- Add dropdowns for article headers.

Note:- This functionality will later be useful for any guided projects or tutorials we include on our website.