Documentation says "page_attributes_misc_attributes" hook is since 4.8

[jfarthing84]

This is due to an incorrect @since declaration in the Docblock. This hook was actually introduced in 4.9.

[jeremyescott]

Did all we really need was a digit changed?

[johnbillion]

In 42203:

Docs: Correct the @since property for the page_attributes_misc_attributes action.

Props jeremyescott, jfarthing84

Fixes #42607

[johnbillion]

In 42219:

Docs: Correct the @since property for the page_attributes_misc_attributes action.

Props jeremyescott, jfarthing84

Fixes #42607

Merges [42203] to the 4.9 branch.