Update to ZipkinExporterOptions (#1510)
Update to ZipkinExporterOptions (#1510)

* Update to ZipkinExporterOptions

* Mistake on pre-compiler message for 4.5.2, versions OTHER than .NET 4.5.2, not below

* Length of line for markdownlint
open-telemetry/opentelemetry-dotnet,open-telemetry/opentelemetry-dotnet,open-telemetry/opentelemetry-dotnet