Docs: Remove extraneous params from block_type_metadata hook

[cr0ybot]

Description

The block_type_metadata hook only accepts one argument, so the doc showing add_filter( 'block_type_metadata', 'filter_metadata_registration', 10, 2 ); confused me. I checked the source of the filter on trac to make sure: https://core.trac.wordpress.org/browser/tags/5.8/src/wp-includes/blocks.php#L215

How has this been tested?

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[gziolo]

Good catch, it's probably a copy and paste issue from block_type_metadata_settings that accepts two params 👍🏻