doc: replace http with https in link from guide (#1386)
doc: replace http with https in link from guide (#1386)

Requests for http://stackoverflow.com/ are redirected to
https://stackoverflow.com/ anyway.
phillipj/new.nodejs.org,yous/new.nodejs.org,nodejs/new.nodejs.org,phillipj/new.nodejs.org,nodejs/new.nodejs.org,yous/new.nodejs.org