troubleshooting-client.mdx: update Client login failures section (#386)

* troubleshooting-client.mdx: update `Client login failures` section

src/pages/how-to/troubleshooting-client.mdx

@@ -340,14 +340,22 @@ You might get errors like below when trying to use Setup Key/different SSO user
 2025-04-08T15:03:04+01:00 WARN client/server/server.go:267: failed login: rpc error: code = PermissionDenied desc = invalid user
 ```
 
+<Note>
+  Starting with the release `0.50.0` the `invalid user` message is more descriptive:
+  `peer is already registered by a different User or a Setup Key`
+</Note>
+
+
 The most notable examples of encountering the issue are:
 
-- shared machines,
+- a shared machine and/or machine previously logged in by somebody else,
 - a machine that was previously logged in using Setup Key, but now attempts SSO login,
-- a machine\'s Peer got removed from the Dashboard without clearing the file,
+- the user makes a mistake and selects
 - the user uses different browser/profile or selects the wrong account during SSO login at the start of the workday,
 
-To resolve the issue, you will need to remove the file manually to use the machine as a different user/Setup Key while the NetBird client daemon is stopped:
+If you know the exact previous Peer which was logged in, you can just delete it from Dashboard without doing anything else and attempt login again.
+
+Otherwise, to resolve the issue, you will need to remove the file manually to use the machine as a different user/Setup Key while the NetBird client daemon is stopped:
 
 1. `netbird service stop`
 2. `sudo rm /etc/netbird/config.json` (*nix) or `rm C:\ProgramData\netbird\config.json` (Windows)