Add deprecation notice to docs

packages/xstate-react/README.md

@@ -115,6 +115,12 @@ A [React hook](https://reactjs.org/hooks) that interprets the given `machine` an
 
 ### `useService(service)`
 
+::: warning Deprecated
+
+In the next major version, `useService(service)` will be replaced with `useActor(service)`. Prefer using the `useActor(service)` hook for services instead, since services are also actors.
+
+:::
+
 A [React hook](https://reactjs.org/hooks) that subscribes to state changes from an existing [service](https://xstate.js.org/docs/guides/interpretation.html).
 
 **Arguments**
@@ -126,7 +132,7 @@ A [React hook](https://reactjs.org/hooks) that subscribes to state changes from
 - `state` - Represents the current state of the service as an XState `State` object.
 - `send` - A function that sends events to the running service.
 
-### `useActor(actor, getSnapshot)`
+### `useActor(actor, getSnapshot?)`
 
 A [React hook](https://reactjs.org/hooks) that subscribes to emitted changes from an existing [actor](https://xstate.js.org/docs/guides/actors.html).
 
@@ -348,11 +354,13 @@ const fetchMachine = createMachine({
   }
 });
 
-const Fetcher = ({ onFetch = () => new Promise(res => res('some data')) }) => {
+const Fetcher = ({
+  onFetch = () => new Promise((res) => res('some data'))
+}) => {
   const [state, send] = useMachine(fetchMachine, {
     actions: {
       load: () => {
-        onFetch().then(res => {
+        onFetch().then((res) => {
           send({ type: 'RESOLVE', data: res });
         });
       }
@@ -361,7 +369,7 @@ const Fetcher = ({ onFetch = () => new Promise(res => res('some data')) }) => {
 
   switch (state.value) {
     case 'idle':
-      return <button onClick={_ => send('FETCH')}>Fetch</button>;
+      return <button onClick={(_) => send('FETCH')}>Fetch</button>;
     case 'loading':
       return <div>Loading...</div>;
     case 'success':