[Doc] Fix <ReferenceInput enableGetChoices> example

[slax57]

Problem

<ReferenceInput enableGetChoices> example returns undefined when q is undefined, which will still fire the query (because enable: undefined) does not disable the query in react-query. It has to return false instead.

Solution

Fix the example to return a boolean all the time.

Additional Checks

• The PR targets master for a bugfix, or next for a feature
• The documentation is up to date