* Use latest mkdocs version 1.4.2
* Add docs_theme to mkdocs watch so it automatically reloads localhost when modifying theme
* Bring in ReadTheDocs breadcrumb theme and fix display issues around "Docs" root breadcrumb
* The problem is CSS, not the breadcrumbs template. Tightly scope offending CSS and remove breadcrumbs template override
* Bring mkdocs ReadTheDocs breadcrumbs theme back in
* Fix pa11y validation issue by replacing breadcrumb a alt attribute with aria-label
* Attribute source of new breadcrumbs file
* Use mkdocs 1.4 or greater with no upper bound
