Documentation improvement for TaylorDiagram class and set_titles_and_labels

[jukent]

PR Summary

Closes #176 and #212

PR Checklist

General

• [x] Make an issue if one doesn't already exist
• [x] Link the issue this PR resolves by adding closes #XXX to the PR description where XXX is the number of the issue.
• [x] Add a brief summary of changes to docs/release-notes.rst in a relevant section for the next unreleased release. Possible sections include: Documentation, New Features, Bug Fixes, Internal Changes, Breaking Changes/Deprecated
• [x] Add appropriate labels to this PR
• [x] Make your changes in a forked repository rather than directly in this repo
• [x] Open this PR as a draft if it is not ready for review
• [x] Convert this PR from a draft to a full PR before requesting reviewers
• [x] Passes precommit. To set up on your local, run pre-commit install from the top level of the repository. To manually run pre-commits, use pre-commit run --all-files and re-add any changed files before committing again and pushing.

Documentation

• [x] Docstrings have been added to all new functions
• [x] Docstrings have been updated with any function changes
• [x] Internal functions have a preceding underscore (_) and have been added to docs/internal_api/index.rst
• [x] User facing functions have been added to docs/user_api/index.rst under their module

Examples

• [x] Any new notebook examples added to docs/examples/ folder
• [x] Clear all notebook cells
• [x] New notebook files added to docs/examples.rst toctree
• [x] New notebook files added to new entry in docs/gallery.yml with appropriate thumbnail photo in docs/_static/thumbnails/

[jukent]

I might have spaced this before (apologies if so), but we should probably add either deprecation warnings or pending deprecation warnings and something in a deprecations section of the release notes about the renamed methods.

Otherwise, looks good.

Thanks @kafitzgerald just added them!