Add Markdown file linter

### Description

Add a Markdown file linter, such as [prettier](https://prettier.io/).

### Expected coding style

ITK contains numerous Markdown files that e.g. describe how to create content links, the ITK release procedure, etc. Adding a Markdown linter tool (e.g. through pre-commit hooks and GHA workflows) would improve readability across such files by standardizing the style.

### Actual coding style

No Markdown linter is in place.

### Versions

`master`.

### Additional Information

Additionally, as some of these files may contain duplicate links, it would be nice to put all links in a single Markdown file, and to be able to include such file in other Markdown files so that the links can be reused. It would reduce maintenance, as links would need to be changed at a single place.

As an example, the reStructuredText syntax contains the `include` directive that allows to do this:
https://docutils.sourceforge.io/docs/ref/rst/directives.html#including-an-external-document-fragment