Install mkdocs-material, and then run mkdocs serve, like this:
$ pip install mkdocs-material
...
$ mkdocs serve
INFO - Building documentation...
INFO - Cleaning site directory
INFO - Documentation built in 0.67 seconds
INFO - [11:54:17] Watching paths for changes: 'docs', 'mkdocs.yml'
INFO - [11:54:17] Serving on http://127.0.0.1:8000/