Show both stable and LTS docs links on homepage

[evanlucas]

Fixes: #305

[fhemberger]

Thanks!

[phillipj]

Wow, fast as lightning there @evanlucas! 👍

[shelleyp]

Please re-open this. You need to show both sets of docs for both active distributions on this page at a minimum https://nodejs.org/api/ - or you need to eliminate this page in favor of links in the front page to both sets of docs. And I would suggest a link to the overall description of the release cycle, too.

Note: the links need to show at the top-level menu, not in small print under the releases.