ENH: Add Author below Title (for Main Page)

[mmcky]

Currently there is no presentation of the authors (from _config.yml displayed on the main page)

while there is on lecture pages

It would be good to add this to the main page (under the title) similar to how a book would be presented. Then we can remove the ad-hoc text

This website presents a set of lectures on quantitative economic modeling, designed and written by [Thomas J. Sargent](http://www.tomsargent.com/) and [John Stachurski](https://johnstachurski.net/).

(optional) It would also be good to enable markdown support in _config.yml to have clickable author names (to their home pages)

[mmcky]

Suggested styling is

[mmcky]

@AakashGfude when you get time could you give me some pointers to how I can implement this. layout.html for example?