NLog.LayoutRenderers.LevelFormat
Format of the ${level} layout renderer output.
FirstCharacter = 1
Render the first character of the level.
FullName = 3
Render the LogLevel full name, expanding Warn / Info abbreviations
Name = 0
Render the LogLevel standard name.
OneLetter = 1
Render the first character of the level.
Ordinal = 2
Render the ordinal (aka number) for the level.
TriLetter = 4
Render the LogLevel as 3 letter abbreviations (Trc, Dbg, Inf, Wrn, Err, Ftl)