Integrate OTEP-83 (Introducing InstrumentationLibrary) into spec

[iNikem]

There is no definition nor description of InstrumentationLibrary in the spec right now. OTEP-83 which introduced the InstrumentationLibrary message was not integrated into spec.

[tigrannajaryan]

There is some (limited) description: https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/glossary.md#instrumentation-library

[andrewhsu]

from the spec issue triage mtg today, looks like PR #800 closes this issue

[arminru]

@andrewhsu #800 solely defined the Zipkin tags for specifying the instrumentation library when exporting to Zipkin but is otherwise unrelated to this issue. This issue is asking for some prose describing what the instrumentation library defined in OTEP 83 is to be added right into the spec.

[arminru]

@iNikem Is the description in the glossary mentioned above and the overview referenced there (https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/overview.md#instrumentation-libraries) sufficient or would you expect more details or better cross-references?

[iNikem]

This issue was requested by @SergeyKanzhelev in #800 (comment). Please ask him for more clarifications :)

[SergeyKanzhelev]

@iNikem @arminru I'd suggest to outline the required fields of the InstrumentationLibrary structure. Otherwise the conversion document we have in Zipkin and Jaeger exporter documents are referring to the name and version that was never defined as required.

Moving nice pseudo-graphics explaining the concept in more details may be a bonus.

[arminru]

@SergeyKanzhelev The fields are defined with the TracerProvider and MeterProvider here:
https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/trace/api.md#tracerprovider-operations
https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/metrics/api.md#obtaining-a-meter
@jmacd proposed to extract these definitions into a common file in #587.

[Oberon00]

I think this is a specific instance of #158.

[andrewhsu]

talked about this at the spec issue triage today, marking as required for ga p3, but doesn't seem like this is big blocker for ga, can bump down to release-after-ga if needed later