add serilogtracing link

[nblumhardt]

Typo in there, mentions Seq while this repo is OTLP.

I think this could be confusing right now, because Serilog.Sinks.OpenTelemetry doesn't support SerilogTracing.

I'd like to open a discussion around whether that might change, since the SerilogTracing.Sinks.OpenTelemetry fork is otherwise pretty much identical to the original code here, and a lot of people working with OTLP will inevitably want to capture some trace data. It'll need a new ticket, though :-)

[liammclennan]

[nblumhardt]

I still think this would be way more compelling (and a bit less confusing) if the message was consider using SerilogTracing with this sink. I'll scope out and raise that ticket, and then loop back here :)