notebooks: Quick update for the "Learn more" section

[validbeck]

Pull Request Description

What and why?

Since we updated the ValidMind Library "portal" in the docs (part of #475), we have cleaner links we can apply to the notebooks / the notebook template. I also democratised the language in this section to apply to more use cases than just model documentation.

old	new

How to test

Review the git diff to see the changes applied across the notebooks that had this section (others missing this section will gain them as I edit the rest of the notebooks): https://github.com/validmind/validmind-library/pull/477/changes

What needs special review?

n/a

Dependencies, breaking changes, and deployment notes

Important

Please also approve and deploy the restructured notebooks to JupyterHub: https://github.com/validmind/demo-environment/pull/25

Release notes

n/a

Checklist

• What and why
• Screenshots or videos (Frontend)
• How to test
• What needs special review
• Dependencies, breaking changes, and deployment notes
• Labels applied
• PR linked to Shortcut
• Unit tests added (Backend)
• Tested locally
• Documentation updated (if required)
• Environment variable additions/changes documented (if required)

[github-actions]

PR Summary

This pull request updates the markdown content across multiple notebooks in the repository. The primary changes involve standardizing and updating the links and descriptive text in the "Discover more learning resources" sections. In several notebooks, outdated URLs and link texts (such as references to 'model-testing' and generic 'Code samples') have been replaced with newer, more descriptive links (e.g., pointing to '/developer/how-to/testing-overview.html', '/developer/how-to/feature-overview.html', and '/guide/samples-jupyter-notebooks.html') that better align with current documentation and feature offerings.

In addition, minor modifications to anchor tags and identifiers (such as changing id names from single underscores to double underscores) ensure improved navigability and consistency within the notebooks. These updates aim to provide clearer guidance to users on how to automate testing, document models, validate processes, and explore related resources, while not affecting any underlying code functionality.

Test Suggestions

• Manually review several notebooks to verify that updated links and descriptions render correctly in the rendered view.
• Click through the updated URLs to ensure they direct users to the correct and intended documentation pages.
• Run a notebook validator to check for any markdown formatting issues or broken anchor links.