[Change Proposal] Add docs_structure_enforced flag in _dev/build/build.yml

Ad part of the [docs improvement project](https://docs.google.com/document/d/1suPRUVDYAqFa1LL-2RIWI7cnj9zI8-LYG0i1eiBfIII/edit?tab=t.0#heading=h.pfm1mse74cxb), we have created a new README structure template to be used for integrations.

To ensure consistency, we want to verify that new integration READMEs follow this structure.

Scope:
This validation will apply only to new integrations for now. Existing integrations will be updated gradually.

To avoid breaking existing integrations, the validation will only be enforced for selected ones. This will be controlled via a flag in the `_dev/build/build.yml` file.

The flag is named: `docs_structure_enforced`

Default value: `false`