v1.0.0-rc.3

• separate application tracer registration from user named tracers
• improve exporter failure logs and include stacktrace
• allows for optional end span timestamp
• Add B3 single propagation format support
• remove unneeded current span functions from otel_tracer
• Drop website_docs and docs_update workflow
• Generate docs with ExDoc
• Update propagators with composite
• Add b3multi option to OTEL_PROPAGATORS
• Expose trace IDs in hex format
• Fix root span sampling
• Do not insert non-recording spans in ETS
• Refactor otel_sampler to use callbacks for setup, should_sample, and decription
• Add test for child span sampling issue
• User defined ssl options in grpc endpoints
• use new api function from_remote_span for propagated span context
• Introduce otel_sampler:new/3 and fix behavior typespec
• Better compliance with status spec
• Add guard to register_tracer
• Be more specific on grpcbox dependency
• Remove unused header in otel_span_ets
• Upgrade Elixir and OTP in GitHub Workflow
• add github action for sending updated docs to otel.io repo
• Remove the OTLP receiver legacy gRPC port(55680) references
• opentelemetry.io: instrumentation docs
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