Add prerequisites and cross-references to AWS Lambda .NET docs

Add a Prerequisites section to help users understand Lambda-specific
requirements before they begin setup. Add Configuration and
Troubleshooting sections with cross-references to main APM docs.

Key additions:
- Prerequisites section explaining Lambda-specific differences
- Links to .NET Core compatibility requirements
- Links to main .NET Core APM docs for background concepts
- Configuration section with Lambda-specific notes
- Troubleshooting section with diagnostic tool references

This improves navigation between Lambda-specific docs and foundational
APM documentation, helping users understand how Lambda differs from
traditional host-based setups.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: lucaspimentel

content/en/serverless/aws_lambda/instrumentation/dotnet.md

@@ -17,6 +17,21 @@ further_reading:
 
 <div class="alert alert-info">Version 67+ of the Datadog Lambda Extension is optimized to significantly reduce cold start duration. <a href="/serverless/aws_lambda/configuration/?tab=datadogcli#using-datadog-lambda-extension-v67">Read more</a>.</div>
 
+## Prerequisites
+
+Before instrumenting your Lambda function:
+
+1. **Review compatibility requirements:** See [.NET Core Compatibility](/tracing/trace_collection/compatibility/dotnet-core) for supported .NET versions and integrations.
+2. **Understand Lambda-specific differences:**
+   - Uses Lambda layers instead of MSI/system installation
+   - Custom instrumentation requires matching layer and NuGet package versions
+   - Environment variables are set in Lambda configuration, not system-wide
+3. **Learn about .NET tracing:** If you're new to Datadog .NET tracing, read [Tracing .NET Core Applications](/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core) for background concepts.
+
+<div class="alert alert-info">
+Looking for traditional host-based setup instead? See <a href="/tracing/trace_collection/automatic_instrumentation/dd_libraries/dotnet-core">Tracing .NET Core Applications</a>.
+</div>
+
 ## Setup
 
 If your application is deployed as a container image, use the _Container Image_ method.
@@ -309,6 +324,21 @@ When using the [Datadog Lambda tracing layer for .NET][9], ensure that a second
 
 You can then add custom spans and span tags using the .NET tracer. For instructions on how to add spans, see [.NET custom instrumentation][10].
 
+## Configuration
+
+Lambda functions support most standard .NET tracer configuration options. See [.NET Core Library Configuration](/tracing/trace_collection/library_config/dotnet-core/) for the full list of environment variables.
+
+**Lambda-specific configuration notes:**
+- Set environment variables in Lambda function configuration, not in code
+- Some Agent-related settings (like `DD_AGENT_HOST`) are managed by the Datadog Extension
+- Tracer version is determined by the Lambda layer version
+
+## Troubleshooting
+
+For common issues and debugging steps, see:
+- [.NET Diagnostic Tool](/tracing/troubleshooting/dotnet_diagnostic_tool)
+- [Troubleshoot Serverless Monitoring](/serverless/guide/troubleshoot_serverless_monitoring)
+
 ## FIPS compliance
 
 {{% svl-lambda-fips %}}