Upgrade Rocket.Chat from 3.x to 4.0, MongoDB from 4.0 to 5.0 via Docker

As of today (20211019), the latest version of Rocket.Chat is 4.0 LTS. MongoDB version 4.0.x is deprecated. So I take this chance to upgrade both to the latest version.

This is a companion discussion topic for the original entry at https://henrywithu.com/upgrade-rocket-chat-from-3-x-to-4-0-mongodb-from-4-0-to-5-0-via-docker/