[DOCS] fix pre merge checks

[kblaszczak-intel]

📝 Description

New pre-merge checks for documentation PRs. This check will run when files in the main docs folder are changed. It will use the exact same build setup as the main documentation publishing job, getting the config files from the docs server, so that no credentials are needed.

The check will be triggered in the main docs folder only because we intend it to host docs from microservice folders as well. The individual microservice "docs" folders will include references to it.

We are planning a follow-up PR to add the feature of attaching the documentation html built for the check as a zip artifact. This way it will be possible to preview the changed articles.

✨ Type of Change

Select the type of change your PR introduces:

• 🐞 Bug fix – Non-breaking change which fixes an issue
• 🚀 New feature – Non-breaking change which adds functionality
• 🔨 Refactor – Non-breaking change which refactors the code base
• 💥 Breaking change – Changes that break existing functionality
• 📚 Documentation update
• 🔒 Security update
• 🧪 Tests
• 🚂 CI

🧪 Testing Scenarios

Describe how the changes were tested and how reviewers can test them too:

• ✅ Tested manually
• 🤖 Ran automated end-to-end tests

✅ Checklist

Before submitting the PR, ensure the following:

• 🔍 PR title is clear and descriptive
• 📝 For internal contributors: If applicable, include the JIRA ticket number (e.g., ITEP-123456) in the PR title. Do not include full URLs
• 💬 I have commented my code, especially in hard-to-understand areas
• 📄 I have made corresponding changes to the documentation
• ✅ I have added tests that prove my fix is effective or my feature works

Thanks for noticing that! The fix is in place, fingers crossed it all works :)