Update description of CPython docs publish frequency

[hugovk]

Describe the bug

https://devguide.python.org/documentation/devguide/ says:

Our devguide workflow uses continuous integration and deployment so changes to the devguide are normally published when the pull request is merged. Changes to CPython documentation follow the workflow of a CPython release and are published in the release.

Expected behavior

The last sentence isn't the whole story; the docs are also updated about once a day. Let's update it to just mention the daily update.