Update transition docs for React 19

src/content/reference/react/startTransition.md

@@ -4,10 +4,10 @@ title: startTransition
 
 <Intro>
 
-`startTransition` lets you update the state without blocking the UI.
+`startTransition` lets you update without blocking the UI.
 
 ```js
-startTransition(scope)
+startTransition(action)
 ```
 
 </Intro>
@@ -18,7 +18,7 @@ startTransition(scope)
 
 ## Reference {/*reference*/}
 
-### `startTransition(scope)` {/*starttransitionscope*/}
+### `startTransition(action)` {/*starttransition*/}
 
 The `startTransition` function lets you mark a state update as a Transition.
 
@@ -41,7 +41,7 @@ function TabContainer() {
 
 #### Parameters {/*parameters*/}
 
-* `scope`: A function that updates some state by calling one or more [`set` functions.](/reference/react/useState#setstate) React immediately calls `scope` with no arguments and marks all state updates scheduled synchronously during the `scope` function call as Transitions. They will be [non-blocking](/reference/react/useTransition#marking-a-state-update-as-a-non-blocking-transition) and [will not display unwanted loading indicators.](/reference/react/useTransition#preventing-unwanted-loading-indicators)
+* `action`: A function that updates some state by calling one or more [`set` functions](/reference/react/useState#setstate). React immediately calls `action` with no parameters and marks all state updates scheduled synchronously during the `action` function call as Transitions. Any async calls awaited in the `action` will be included in the transition, but currently require wrapping any `set` functions after the request in an additional `startTransition` (see [Troubleshooting](#react-doesnt-treat-my-state-update-after-await-as-a-transition)). State updates marked as Transitions will be [non-blocking](#marking-a-state-update-as-a-non-blocking-transition) and [will not display unwanted loading indicators.](#preventing-unwanted-loading-indicators).
 
 #### Returns {/*returns*/}
 
@@ -53,7 +53,9 @@ function TabContainer() {
 
 * You can wrap an update into a Transition only if you have access to the `set` function of that state. If you want to start a Transition in response to some prop or a custom Hook return value, try [`useDeferredValue`](/reference/react/useDeferredValue) instead.
 
-* The function you pass to `startTransition` must be synchronous. React immediately executes this function, marking all state updates that happen while it executes as Transitions. If you try to perform more state updates later (for example, in a timeout), they won't be marked as Transitions.
+* The function you pass to the of `startTransition` is called immediately, marking all state updates that happen while it executes as Transitions. If you try to perform state updates in a `setTimeout`, they won't be marked as Transitions.
+
+* You must wrap any state updates after any async requests in another `startTransition` to mark them as Transitions. This is a known limitation that we will fix in the future (see [Troubleshooting](#react-doesnt-treat-my-state-update-after-await-as-a-transition)).
 
 * A state update marked as a Transition will be interrupted by other state updates. For example, if you update a chart component inside a Transition, but then start typing into an input while the chart is in the middle of a re-render, React will restart the rendering work on the chart component after handling the input state update.