Documentation issue - .NET links have moved to new repo

[jbma2z]

Links to github repos in this section are no longer valid.
https://aws-otel.github.io/docs/getting-started/dotnet-sdk/manual-instr#instrumenting-net-applications

New repo was created here:
https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation

[mhausenblas]

Thanks!