Update guide-disappearance.md (testing-library#412)

Update to mention `waitFor` as it will replace `wait` and change `waitForElement` example to use `findBy` query instead.

Author: danieljcafonso

docs/guide-disappearance.md

@@ -17,12 +17,12 @@ test('movie title appears', async () => {
  // element is initially not present...
 
  // wait for appearance
- await wait(() => {
+ await waitFor(() => {
  expect(getByText('the lion king')).toBeInTheDocument()
  })
 
  // wait for appearance and return the element
- const movie = await waitForElement(() => getByText('the lion king'))
+ const movie = await findByText('the lion king')
 })
 ```
 
@@ -41,9 +41,9 @@ test('movie title no longer present in DOM', async () => {
 
 Using
 [`MutationObserver`](https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver)
-is more efficient than polling the DOM at regular intervals with `wait`.
+is more efficient than polling the DOM at regular intervals with `waitFor`.
 
-The `wait` [async helper][async-api] function retries until the wrapped function
+The `waitFor` [async helper][async-api] function retries until the wrapped function
 stops throwing an error. This can be used to assert that an element disappears
 from the page.
 
@@ -52,7 +52,7 @@ test('movie title goes away', async () => {
  // element is initially present...
  // note use of queryBy instead of getBy to return null
  // instead of throwing in the query itself
- await wait(() => {
+ await waitFor(() => {
  expect(queryByText('i, robot')).not.toBeInTheDocument()
  })
 })