`npx --call` uses the native shell. This means the shell code used by the task does not work on Windows.
 After quite a bit of unsuccessful efforts, I decided that it is simply too difficult to use npx for this application on
 Windows. So the Windows user is required to have markdown-link-check installed and in PATH. Because Task uses an
 integrated shell interpreter, shell code is usable as long as it is not wrapped in a `npx --call` command.

On every push and pull request that affects relevant files, and periodically, check the repository's Markdown files for
problems:
- Use markdownlint to check for common problems and formatting.
- Use markdown-link-check to check for broken links.
The Arduino tooling Markdown style is defined by the `.markdownlint.yml` file.
In the event the repository contains externally maintained Markdown files, markdownlint can be configured to ignore them
via a `.markdownlintignore` file:
https://github.com/igorshubovych/markdownlint-cli#ignoring-files
markdown-link-check is configured via the `.markdown-link-check.json` file:
https://github.com/tcort/markdown-link-check#config-file-format
This duplicates the link check capability previously provided by the "Check links" workflow, so that has been removed.