Change field description in ettings

[ackvf]

The field to ignore extensions says

Enter one extension per line (full name)

but that's really ambiguous and also wrong.

the full name is: "Settings Sync"
the identifier is: "shan.code-settings-sync"

Maybe you could change the help in the Ignored Extensions field in the sync settings to

Enter one extension identifier per line.
Identifier can be found in the marketplace next to extension name.
For example, this extension's identifier is shan.code-settings-sync

mentioned here #982 (comment)