Disabling Prototype Extensions guide needs review

[elwayman02]

https://github.com/ember-learn/guides-source/blob/master/guides/release/configuring-ember/disabling-prototype-extensions.md

https://guides.emberjs.com/release/configuring-ember/disabling-prototype-extensions/

Prototype extensions have largely been phased out of Octane patterns, so this is a good time to rethink how we document them (if at all).

Potentially Related: https://github.com/ember-learn/guides-source/issues/1539

[elwayman02]

Related context from Discord discussions starts here: https://discord.com/channels/480462759797063690/480777444203429888/852288158892294165