Review Discord channels and text

[anibalsolon]

Take a look through all the channels, if they are needed or if needs to create others, their descriptions, and initial content.

Server

• [x] Security measures: membership screening
• [x] Hide everything while Code of Conduct was not accepted
• [x] Stage channel

Roles

• [x] 3 timezones + 1 on-site
• [x] 4 time/site channels
• [x] limit who can show camera on main stage
• [x] event org and mentors with different colors