Update java config docs for OTLP endpoint

[jaydeluca]

Context

My intent is to clarify the configuration options for the otel.exporter.otlp.endpoint configuration option. I think the current description could be interpreted to mean that It is needed to supply the v1/{signal} postfix for the endpoint, when that is only required when using the otel.exporter.otlp.{signal}.endpoint option.

What is being changed

Updated description for otel.exporter.otlp.endpoint removing references to the v1/{signal} postfix, and updated the reference to the default value of http://localhost:4318 instead of http://localhost:4318/v1/{signal}

Updated the description for otel.exporter.otlp.{signal}.endpoint to include the note about needing to include the postfix to the provided endpoint

[breedx-splk]

I agree, this helps to clarify the settings. Thanks @jaydeluca !