[DOC] Fix the distributes tracing guide

[Gaganjuneja]

What do you want to do?

• [X] Request a change to existing documentation
• [ ] Add new documentation
• [ ] Report a technical problem with the documentation
• [ ] Other

Tell us about your request. Provide a summary of the request and all versions that are affected.

1. Update the document to add the setting telemetry.feature.tracer.enabled: true which is a prerequisite to enable this feature.
2. Fix typo - typo related to the grpc configuration for traces, the class in the docs is mentioned incorrectly telemetry.otel.tracer.span.exporter.class=org.opensearch.telemetry.tracing.exporter.OtlpGrpcSpanExporterProvider, while it should have the following value telemetry.otel.tracer.span.exporter.class: io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter

What other resources are available? Provide links to related issues, POCs, steps for testing, etc. https://github.com/opensearch-project/OpenSearch/issues/13323