Updated content

[nylen]

Updated: https://docs.classicpress.net/installing-classicpress/installing-with-composer/

Out of date: https://classicpress.readthedocs.io/en/latest/installation/composer.html#installation-composer

TODO:

• Full list of pages
• Sync content ([semi-]automated using e.g. WP REST API and pandoc, or one more manual sync just before switching over)

[johnalarcon]

Here's the list of pages.