Update upgrade guide

modules/docs/mdx/12.0-UPGRADE-GUIDE.mdx

@@ -281,6 +281,34 @@ component composing them.
 </Combobox>
 
 // Better - create a specialized component
+const useMyComboboxInput = composeHooks(
+  // or your own model that extends `useComboboxModel`
+  createElemPropsHook(useComboboxModel)(model => {
+    return {
+      // anything you need your input to do
+    }
+  }),
+  useComboboxInputArbitrary,
+  useComboboxInput
+)
+
+const MyComboboxInput = createSubcomponent(TextInput)({
+  // or your own model that extends `useComboboxModel`
+  modelHook: useComboboxModel,
+  elemPropsHook: useMyComboboxInput,
+})((elemProps, Element) => {
+  // return a TextInput
+  return <Element {...elemProps} />
+
+  // return an InputGroupgs
+  return (
+    <InputGroup>
+      <InputGroup.InnerStart>{/* Icon or something */}</InputGroup.InnerStart>
+      <InputGroup.Input as={Element} {...elemProps} />
+      <InputGroup.InnerEnd><InputGroup.ClearButton /></InputGroup.InnerEnd>
+    </InputGroup>
+  )
+})
 ```
 
 ### Form Field
@@ -537,7 +565,7 @@ const theme: PartialEmotionCanvasTheme = {
 ```
 
 `Select` has been refactored to use `useComboboxInputConstrained` to sync the model and the `input`
-element regardless of the source. This makes the `Select` be a controllable component.
+element regardless of the source. This makes the `Select` a controllable component.
 
 ### Text Area
 

modules/react/combobox/stories/Combobox.mdx

@@ -30,13 +30,14 @@ pick from these values, but cannot input a value outside the options provided. C
 comboboxes use the [useComboboxInputConstrained](#usecomboboxinputconstrained) hook and often have
 two separate `input` elements.
 
-- user input - This is the visible input. It should contain user-friend values. Calls to `.focus()`
-  or `.blur()` are redirected to this input. Any prop passed to the `*.Input` component that is not
-  directly related to forms will be passed here (i.e. `data-testid`, `aria-*`, etc).
-- form input - This input is only visible to forms. The `value` will usually be server IDs. If the
-  combobox options don't have an ID and only use user values, the value of this input will be the
-  same as the user input. Any prop related to the function of forms will be passed here. For
-  exampple, the `name` attribute will be passed here. The `ref` will pointed to this element.
+- user input - This is the visible input and it should contain user-friendly values. Calls to
+  `.focus()` or `.blur()` are redirected to this input. Any prop passed to the `*.Input` component
+  that is not directly related to forms will be passed here (i.e. `data-testid`, `aria-*`, etc).
+
+- form input - This input is only visible to forms and the `value` will usually be server IDs. If
+  the combobox options don't have an ID and only use user values, the value of this input will be
+  the same as the user input. Any prop related to the function of forms will be passed here. For
+  example, the `name` attribute will be passed here. The `ref` will be pointed to this element.
 
 ### Arbitrary