Update documentation on the website to the latest stable release #171
Description
Currently, the webpage https://auto.gluon.ai/cloud/stable/index.html displays an older version of the documentation (v0.3.1) instead of the latest stable release (v0.4.2).
As a side note, it would be convenient to add a redirect from https://auto.gluon.ai/cloud (currently results in an error) to https://auto.gluon.ai/cloud/stable/index.html. This way the users won't have to type the full address including stable/index.html to visit the documentation webpage.