Improve wording / understanding of the admin screen

[lebouquetin]

Contribution guidelines

• I've read the contribution guidelines and wholeheartedly agree

I've found a bug and checked that ...

• ... I understand that not following the below instructions will result in immediate closure and/or deletion of my issue.
• ... I have understood that this bug report is dedicated for bugs, and not for support-related inquiries.
• ... I have understood that answers are voluntary and community-driven, and not commercial support.
• ... I have verified that my issue has not been already answered in the past. I also checked previous issues.

Description

This issue is related to the subject created on galae.net community space - https://community.galae.net/ui/workspaces/1/contents/thread/995

Statistics and quota may be misunderstood.

On the screenshot:

Quota :
2.3 GiB: total quota dedicated to the domain name.
2.0 GiB: quota already dedicated to mailboxes (300 MiB still available for dispatch)
Statistics
3687 : number of emails
281.1 MiB : storage really used

Expected (one of or a combination of all) :

• add a help text in the headers in order to explain meaning of each value.
• add a title text on values
• add a help button + text on every field
• ...