[PYTHON] Config value:'pages'. Warning: The'pages' configuration option has been deprecated and will be removed in a future release of MkDocs. Use'nav' instead.

--Environment --Windows10 Pro version 1909 - Python 3.8.5 - mkdocs, version 1.1.2

Event: I was warned when I built MkDocs

> mkdocs build
WARNING -  Config value: 'pages'. Warning: The 'pages' configuration option has been deprecated and will be removed in a future release of MkDocs. Use 'nav' instead.
INFO    -  Cleaning site directory
# ...abridgement...

Cause: mkdocs.yml uses the deprecated pages

pages:
  -Advance preparation: 'index.md'

Version 1.0 (2018-08-03) The pages configuration setting has been renamed to nav The pages configuration setting is deprecated and will issue a warning if set in the configuration file. The setting has been renamed nav. Release Notes - MkDocs

(Rough translation) I changed the name of the pages setting to nav, so I'll warn you that pages is deprecated and used, so change it.

Action: Change pages to nav

nav:
  -Advance preparation: 'index.md'