Is your feature request related to a problem? Please describe.
I have a quite complex logging pipeline having at least two levels of nesting via configuration.WriteTo.Logger(nestedLogger). The problem is, I can't dispose all of it in one go, because nested loggers are not disposed when parent logger is.

Describe the solution you'd like
I would like to be able to specify that I want nested logger to be disposed with the pipeline, i.e.:

configuration.WriteTo.Logger(nestedLogger, dispose: true)

This can be easily accomplished by passing the flag down to SecondaryLoggerSink.

Describe alternatives you've considered

• WriteTo.Logger(Action<LoggerConfiguration>) which creates logger internally and disposes of it.
  I was able to replace only on of my usages with this one, because in other cases the logger is already created.
• WriteTo.Sink(logger) (using the fact that Serilog.Core.Logger is actually a ILogEventSink).
  This way the events pushed to logger are not copied so they can (and will be, in my case) modified by nested logger's enrichment. Also, feels hack-ish and requires access to Logger instead of ILogger.
• WriteTo.Logger(lc => lc.WriteTo.Sink(logger)).
  This, probably, will work (and I might settle for this in a short-term), but, same as above, requires access to Logger and feels even more hack-ish.

BTW, I'd add a simple overload in my own code, but both SecondaryLoggerSink and LogEvent.Copy are internal.