Add tips for running a local server

[cvan]

Ideally, folks use one of the A-Frame Boilerplate. But, there are other options, which we should briefly document/link to. It seems not every/many folks are using the Boilerplate w/ Node+npm are instead referencing the aframe.min.js URL from our site or downloading it and including it in their own projects.

Possible inspiration to draw from/links to include:

• https://github.com/mrdoob/three.js/wiki/How-to-run-things-locally
• https://chrome.google.com/webstore/detail/web-server-for-chrome/ofhbbkphhbklhfoeikjpcbhemlocgigb (referenced by someone in A-Frame Slack)
• https://www.browsersync.io/

[cvan]

(Perhaps this belongs in the FAQ and/or the docs. If FAQ, I can move this issue to the aframevr/aframe repo.)

[ngokevin]

On Windows, my brother used Mongoose (.exe) with success.

[cvan]

nice, cool. @321C4 has used Prepros https://prepros.io/ in the past

[ngokevin]

Added to Getting Started page links to mongoose. If you see something else it can be added, send a PR