Rocket.chat: Create a Help tab on flex-tab-bar

[karlprieb]

Add a tab called Help on flex-tab-bar and move formatting tips to the new tab.

@RocketChat/core

[geekgonecrazy]

This would take into account the stuff located below the text input also?

I ask because frequently notice this gets really screwy especially on mobile when the text "someone is typing" is added

[engelgabriel]

Yes, we will remove the stuff located below the text input, and add something like this on the side tab:

[karlprieb]

We decide to move this to the bottom of message box, so I will close this issue.