Simple 'welcome' tutorial page

[lampholder]

As a new user logging in for the first time, I should understand my legal relationship with Riot/Matrix and know how to get started with the app

element-hq/element-web#2430 describes some of the thinking around this.

This task is potentially a subset of #4. Matthew's suggestion is to solve with a configurable per-team lump of HTML, served up and rendered within the app on first login.

Matthew refers to this as a MOTD, but it's unclear whether the scope of this is to deliver a daily message with every login (or every day) or if this is just targeted at brand new users (or whether there are any other circumstances under which a user would encounter this screen - first (re)install of the app, first visit in a long time, etc.).

[lampholder]

@ara4n when you say MOTD - are you picturing something that might actually appear daily, or more of the standard IRC MOTD experience that appears once when you connect to the server?