"I need more than 300 emails per month" FAQ needs work

**Description of the issue**
The "I need more than 300 emails per month" FAQ is contradictory and needs clarification.

**Location of the issue**
https://github.com/Hubs-Foundation/hubs-docs/blob/master/docs/faq.md#i-need-more-than-300-emails-per-month

**Expected result from remediation**
A clear and concise description of how you can get more emails from Scaleway.

**Screenshots of the issue**
N/A

**Hardware the issue was observed on**
- Device: Desktop
- OS: GNU/Linux
- Browser: Firefox

**Additional context/notes**
Part of: https://github.com/Hubs-Foundation/hubs-docs/issues/261

Open docs/faq.md at the “I need more than 300 emails per month” section and compare the existing statements for contradictions. Rewrite that FAQ so it clearly and concisely explains how to get more emails from Scaleway. Done means the section is consistent and answers the stated question without ambiguity.

Written by the indexing model from the issue text.