Contributing guidelines

• I've read the contributing guidelines and wholeheartedly agree

I've found a bug and checked that ...

• ... the documentation does not mention anything about my problem
• ... there are no open or closed issues that are related to my problem

Description

I followed the instructions here:
https://docs.docker.com/build/building/opentelemetry/
but did not get any buildx spans.

Expected behaviour

Both buildx and buildkitd spans

Actual behaviour

Only buildkitd spans

Buildx version

HEAD

Docker info

n/a

Builders list

n/a

Configuration

n/a

Build logs

No response

Additional info

we forgot to import the exporter 😭