[Doc] Explain openOnFocus in <AutocompleteInput> with StrictMode

Author: djhi

docs/AutocompleteArrayInput.md

@@ -212,6 +212,8 @@ const CreateRole = () => {
 ```
 {% endraw %}
 
+**Tip**: In development with `React.StrictMode`, you may run into an issue where the `<AutocompleteInput>` menu reopens after clicking the create item when the [`openOnFocus`](https://mui.com/material-ui/api/autocomplete/#autocomplete-prop-openOnFocus) prop is set to `true` which is the default with React-admin. If that bothers you, set the `openOnFocus` prop to `false`.
+
 If you just need to ask users for a single string to create the new option, you can use [the `onCreate` prop](#oncreate) instead.
 
 If you're in a `<ReferenceArrayInput>` or `<ReferenceManyToManyInput>`, the `handleSubmit` will need to create a new record in the related resource. Check the [Creating New Choices](#creating-new-choices) for an example. 

docs/AutocompleteInput.md

@@ -219,6 +219,8 @@ const CreateCategory = () => {
 ```
 {% endraw %}
 
+**Tip**: In development with `React.StrictMode`, you may run into an issue where the `<AutocompleteInput>` menu reopens after clicking the create item when the [`openOnFocus`](https://mui.com/material-ui/api/autocomplete/#autocomplete-prop-openOnFocus) prop is set to `true` which is the default with React-admin. If that bothers you, set the `openOnFocus` prop to `false`.
+
 If you want to customize the label of the "Create XXX" option, use [the `createItemLabel` prop](#createitemlabel).
 
 If you just need to ask users for a single string to create the new option, you can use [the `onCreate` prop](#oncreate) instead.