Docs/fix duplicate block attr slug

[dknieriem]

Description

Fixes #23978

Updates "Create Block" Tutorial Doc filenames in order to force unique slugs for two "block-attribute" pages

How has this been tested?

• Ran npm docs:build
• Verified that all links for the "Create Block" tutorial still work
• Verified that links to the Blocks API page "block attributes" now link to the correct page

Screenshots

N/A

Types of changes

Docs update

Checklist:

• My code is tested.
• [n/a] My code follows the WordPress code style.
• [n/a] My code follows the accessibility standards.
• [n/a] My code has proper inline documentation.
• [n/a] I've included developer documentation if appropriate.
• [n/a] I've updated all React Native files affected by any refactorings/renamings in this PR.

[ajitbohra]

maybe we can simply rename slug block-attributes to attributes

cc: @mkaz

[mkaz]

@ajitbohra Agreed. Switched in #24244

Thanks for the PR and suggestion, howeverchanging so many links will require putting redirects in place since those pages are already linked elsewhere. It will be easier to just switch to attributes.md and use the longer names in the future.