Remove outdated pre-TelemetryConfig OTel documentation (#855)

* Remove outdated pre-TelemetryConfig OTel documentation

- Remove the large 'Application-Level Instrumentation' section from
  docs/observability/opentelemetry.md (614 lines) that described manual
  OTel setup which is now handled by the built-in TelemetryConfig
- Replace --disable-telemetry CLI arg example in docs/setup/local-cli.md
  with --no-auto-update to avoid confusion with TelemetryConfig
- Update link descriptions in getting-started.md and index.md to reflect
  the trimmed OTel doc scope

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: 3 people

docs/getting-started.md

@@ -1510,7 +1510,7 @@ Trace context is propagated automatically — no manual instrumentation is neede
 - **SDK → CLI**: `traceparent` and `tracestate` headers from the current span/activity are included in `session.create`, `session.resume`, and `session.send` RPC calls.
 - **CLI → SDK**: When the CLI invokes tool handlers, the trace context from the CLI's span is propagated so your tool code runs under the correct parent span.
 
-📖 **[OpenTelemetry Instrumentation Guide →](./observability/opentelemetry.md)** — detailed GenAI semantic conventions, event-to-attribute mapping, and complete examples.
+📖 **[OpenTelemetry Instrumentation Guide →](./observability/opentelemetry.md)** — TelemetryConfig options, trace context propagation, and per-language dependencies.
 
 ---
 
@@ -1525,7 +1525,7 @@ Trace context is propagated automatically — no manual instrumentation is neede
 - [Using MCP Servers](./features/mcp.md) - Integrate external tools via Model Context Protocol
 - [GitHub MCP Server Documentation](https://github.com/github/github-mcp-server)
 - [MCP Servers Directory](https://github.com/modelcontextprotocol/servers) - Explore more MCP servers
-- [OpenTelemetry Instrumentation](./observability/opentelemetry.md) - Add tracing to your SDK usage
+- [OpenTelemetry Instrumentation](./observability/opentelemetry.md) - TelemetryConfig, trace context propagation, and per-language dependencies
 
 ---
 

docs/index.md

@@ -67,7 +67,7 @@ Detailed API reference for each session hook.
 
 ### [Observability](./observability/opentelemetry.md)
 
-- [OpenTelemetry Instrumentation](./observability/opentelemetry.md) — built-in TelemetryConfig, trace context propagation, and application-level tracing
+- [OpenTelemetry Instrumentation](./observability/opentelemetry.md) — built-in TelemetryConfig and trace context propagation
 
 ### [Integrations](./integrations/microsoft-agent-framework.md)