Docs: Update the content of the API version 3 section in the Block API Reference (#65375)

Co-authored-by: t-hamano <[email protected]>
Co-authored-by: fabiankaegy <[email protected]>

Author: t-hamano

docs/reference-guides/block-api/block-api-versions.md

@@ -3,7 +3,7 @@
 This document lists the changes made between the different API versions.
 
 ## Version 3 (>= WordPress 6.3)
-- The post editor will be iframed if all registered blocks have a Block API version 3 or higher and the editor has no classic meta boxes below the blocks. Adding version 3 support means that the block should work inside an iframe, though the block may still be rendered outside the iframe if not all blocks support version 3.
+- The post editor will be iframed if all registered blocks have a Block API version 3 or higher. Adding version 3 support means that the block should work inside an iframe, though the block may still be rendered outside the iframe if not all blocks support version 3.
 
 ## Version 2 (>= WordPress 5.6)