Update "Use create_posts capability"

[stevejburge]

Let's move "Use create_posts capability" to the Advanced tab

[agapetry]

@stevejburge This is a commonly desired and broadly influential setting that would be good to clarify, not sideline. It is logically correlated to the Filtered Post Types settings:

• Enabling a post type for filtering causes type-specific "edit_" capabilities to be enforced for that post type
• Enabling the "Use create_posts" setting causes the "create_" capability to be enforced for post creation

[stevejburge]

OK, @agapetry. We'll keep it in place and work on clarifying the text.