Fix handling of `---` separator inside code-blocks

## Description

Apparently the `doc-builder` does not handle well the `---` separators within a YAML code-block when rendering / building the MDX files out of the MD files.

For context, the `---` is being used to split the Kubernetes Deployment from the Service in a Kubernetes manifest, I made the `doc-builder` action pass with [this change](https://github.com/huggingface/Google-Cloud-Containers/pull/133/commits/7b8929870aa01a87e81f1f48070b13d7c36ec3a6), so assuming that there's an issue on handling the `---` inside a code-block.

[Here's the detailed error in the CI](https://github.com/huggingface/Google-Cloud-Containers/actions/runs/12314942755/job/34372086651) in case that's helpful, thanks in advance :hugs: