update docs for `manage-users` and user API provider

[mcgr0g]

Enhancement Type

Improve an existing feature

Describe the enhancement

Documentation Link: Server Properties - OPs/Administrators

Problem
When using the manage-users command to add an OP/whitelisted player with an Xbox/Microsoft Account (MSA), the container fails to start with the error:

[mc-image-helper] ERROR: Invalid parameter provided for 'manage-users' command: Could not resolve user from Playerdb

The Mojang API (https://api.mojang.com/users/profiles/minecraft/:username) returns:

{"errorMessage": "Couldn't find any profile with name :username"}

Even though the profile exists on:

• Xbox Profile
• Minecraft.net Profile

Root Cause
Different Java Profile Name and xbox gametag.

Solution
Use username from Java Profile Name. Or change it there to gametag value.

[itzg]

I suppose a note would help but I would hope that would be implied when using the Java edition server instead of the Bedrock edition

https://github.com/itzg/docker-minecraft-bedrock-server

[mcgr0g]

I tested both servers but I don't understand your position, sorry.

In the bedrock server, it was enough to specify the UID, which is visible in the log when the player joins.
In the java server, these UIDs will not work, there you need to use username or gametag or another uid.

In my case, one of the players used profile renaming after registering in Xbox, but forgot to do it in the Minecraft profile.
Honestly, I did not know that between these backends there is not full synchronization of accounts.