Add `moment-timezone` to the Moment docs

[j-f1]

@denilsonsa on Trello:

We already have Moment.js documentation. (See Moment.js) However, it is missing the documentation for moment-timezone, which is an optional part of moment.js. I imagine the scraper would be mostly the same. You could even group both documentation pagess (moment and moment-timezone) under the same "Moment.js" project insie devdocs. https://momentjs.com/timezone/docs/