Cleanup of links out to the ValidMind Library docs

[validbeck]

Internal Notes for Reviewers

Follow-up to validmind/documentation#668:

• get-started-validmind-library.qmd renamed to just validmind-library.qmd, so I modified the links and references to the outdated title
• I noticed my mini-template actually had a broken link to a doc that NEVER existed, so I fixed that my bad 💀: main...beck/sc-8728-followup#diff-d52fab9367df11b7364d624c04952bfbdf46288ade172778fb6b8bbf49a1468a
• Added the ToC extension to the template README as it's proving to be quite useful:

  validmind-library/notebooks/templates/README.md

  Line 20 in 48c82b1

  ## Add table of contents

EDIT:

Added an intro block to 101 as I liked the beginnings of the one Michael added in the validator notebook:

[nrichers]

LGTM, just a minor comment you can commit. 🚀

Related, we likely should set up a redirect for https://docs.validmind.ai/developer/ (and https://docs.validmind.ai/guide/, similar to how we already do this for the training portal.

[github-actions]

PR Summary

This pull request updates various documentation links across multiple files in the project. The changes involve updating the URL paths from get-started-validmind-library.html to validmind-library.html in markdown files, Jupyter notebooks, and R markdown files. This change ensures that all references to the ValidMind Library documentation are consistent and point to the correct location.

The affected files include:

• README.md
• README.pypi.md
• Various Jupyter notebooks in the notebooks/code_samples and notebooks/how_to directories
• R markdown files in the notebooks/code_sharing/r directory

These updates are intended to improve the accuracy and accessibility of the documentation links for users exploring the ValidMind Library resources.

Test Suggestions

• Verify that all updated links in markdown files and Jupyter notebooks correctly navigate to the intended ValidMind Library documentation page.
• Check that there are no broken links in the affected files after the update.
• Ensure that the documentation renders correctly in both markdown and Jupyter notebook formats.
• Test the navigation within Jupyter notebooks to confirm that internal links (e.g., table of contents) are still functional.