Document discrepancy with spec or loosen spec for default value of exporter endpoint

[anuraaga]

I randomly noticed the default value for endpoint for exporter is https://localhost

https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#configuration-options

Java uses http://localhost - I think fixing this now would be too disruptive to existing users without enough benefit. Should this be documented here somehow or the spec wording loosened to allow it? FWIW, I believe https://localhost has no real user case and suspect where secure is implemented as the default in the SDK, 100% of users are setting the variable themselves - in case that matters here.

[carlosalberto]

@anuraaga We briefly discussed this in the Maintainers meeting and we are fine with loosening this (with a SHOULD, that is). Can you prepare such a PR? Else I can help with it.