[DOC] delete dead documentation page docs/introduction.rst

[kabirvashisht4-glitch]

Reference Issues/PRs

Fixes #1025

What does this implement/fix? Explain your changes.

While going through the skpro codebase I noticed
the "boston data" link in docs/introduction.rst
was broken and pointing to a 404 page.

The link was pointing to:
http://scikit-learn.org/stable/modules/generated/sklearn.datasets.load_boston.html

This page no longer exists because sklearn
permanently removed load_boston in version 1.2
(2022) due to ethical concerns around the dataset.

Changes made in docs/introduction.rst:

• replaced broken boston data link with california
  housing dataset URL which is the official sklearn
  replacement
• updated all text mentions of boston to
  california housing throughout the file

Does your contribution introduce a new dependency? If yes, which one?

No new dependencies introduced.

What should a reviewer concentrate their feedback on?

• The link replacement in docs/introduction.rst
• All text mentions of boston updated to
  california housing correctly

Did you add any tests for the change?

No tests needed as this is a documentation
only change.

Any other comments?

While investigating this issue I also found
that docs/introduction.rst references two
example files via literalinclude directives:

• examples/simple.py
• examples/workflow.py

Both files were deleted in PR #271 (Apr 2024)
but the references in docs/introduction.rst
were never removed. This will be raised as a
separate bug issue.

PR checklist

For all contributions

• I've added myself to the list of contributors
  with any new badges I've earned :-)
• The PR title starts with [DOC]

[fkiraly]

This looks like a dead documentation page. This is from skpro 1.0, using methods that have been removed since.

Have you checked whether this is still live? If no, just delete the rst file. If yes, please replace by another example from the tutorial notebook.

[kabirvashisht4-glitch]

Hi @fkiraly, thanks for the review!

I checked and the introduction.rst file is not
linked anywhere in the docs - it only references
itself. So it looks like this is indeed a dead
page from skpro v1.0.

I will go ahead and delete the entire
introduction.rst file.