explain `netdev`(VPN, Bluetooth) and other permissions

[The-Nickname]

Hey, I hope this is the correct place to raise this issue.
In the docs it is explained that the behavior of blueman requiring admin(root) privileges can be changes by adding a user to the netdev group.

I was always wondering how to change this behavior until I read the User Guide and discovered it by change.
When setting up a VPN I found it somewhat annoying that I also always needed admin(root) permissions to enable it,
however after I added the netdev permission to my user to easily toggle Bluetooth, I found out that apparently it also allowed me to toggle the VPN connection without a root(admin) prompt.

This is why I would like to suggest, to add a mention of the VPN permissions being managed by netdev as well.
I could open a pull request and add a new section called VPN next to the Bluetooth section,

however I was thinking that reworking the entire section into something called "Permissions" might be more useful and also answering questions like:

• What other permissions does netdev influence.
• What other useful groups might there be a user might want to add?
  • And what do they do?

[Jeremy7701]

https://wiki.debian.org/SystemGroups might be of interest.
So "netdev: Members of this group can manage network interfaces through the network manager and wicd."