Fix path to rust examples in github action

[nepet]

Fixes the path to the rust examples in the github action.

[nepet]

Please wait before merging this, I am going to add some CI improvements as well. Currently we are blind if the docs can be built without an error on PRs. We should change that to a more robust system where we

• build docs on PR if we changed something in docs/ or examples
• reuse build workflow and deploy docs on merge to main if we changed something in docs/ or examples

[cdecker]

Let's open a new issue for this, we need to get the docs back to working order, and what you're proposing is new functionality anyway.