[Doc] improve AutocompleteInput create example

[Cimanel]

Problem

Current examples of in the docs leverage useCreate, and require calling create manually with data coming from self-managed controlled inputs.

It’s actually simpler to leverage , which removes the need to call create directly, and opens the ability to use

along with RA Input components.

Solution

Update the doc examples to use instead.

How To Test

the story to test: http://localhost:9010/?path=/story/ra-ui-materialui-input-autocompleteinput--inside-reference-input-with-creation-support

Additional Checks

• The PR targets master for a bugfix or a documentation fix, or next for a feature
• The PR includes unit tests (if not possible, describe why)
• The PR includes one or several stories (if not possible, describe why)
• The documentation is up to date

Also, please make sure to read the contributing guidelines.

[slax57]

Other than that, LGTM! You're on the right track!