Clear up what account should be used by the Mattermost system admin

[Gaibhne]

The instructions are very unclear on what account should be used by the Mattermost system admin when setting up the integration. Surely, I'm not supposed to use my personal account, since later on it details how users can authorize their own accounts. But what is the initial account used for the OAuth access for, what account should it be, and what permissions does it have to have ?

[Gaibhne]

Addon: I'm not just asking for myself, but as a request to update the instructions in that regard; a single comment (I assume something like 'a service account with the abc scope, used to fetch x, z and y') would probably be enough as a first improvement.