Provide guidance when implementing interfaces that do not conform to Go versioning policy

[mx-psi]

Problem Statement

As mentioned in #3277, #3968 and elsewhere, some interfaces declared in modules from this repository do not conform to the standard Go versioning policy. However, there is no guidance on how to handle these in some cases.

Proposed Solution

Similar to https://pkg.go.dev/go.opentelemetry.io/otel/metric#hdr-API_Implementations, provide guidance on alternatives to implement trace interfaces that may break on minor versions. See #3968 (comment) for rationale and further suggestions.

Prior Art

See https://pkg.go.dev/go.opentelemetry.io/otel/metric#hdr-API_Implementations and #3968 (comment)

Additional Context

Outcome of discussion on #3968