New page: Migrate WordPress Multisite into WordPress sites

[javiercasares]

File: multisite/multisite-sites.md

This is a new page, like a copy of multisite/sites-multisite.md, but in reverse.

Some reference: Migrate a WordPress from MultiSite to Simple.

If you add documentation from another WordPress.org page, indicate it in the Changelog or in the comments of this issue.

To-Do

• [ ] Create the page and contents

[jerico]

The reference is based on instruction using cPanel. Should the reverse also assume using cPanel? Is it okay to recommend a plugin to simplify the process?

[javiercasares]

The first idea is to do something native, but we can add also a cPanel section. There is no problem there :)