docs(vision): fix usage example in readme

packages/@sanity/vision/README.md

@@ -18,12 +18,12 @@ Vision is a plugin for Sanity Studio for testing GROQ queries. It features:
 ```ts
 // `sanity.config.ts` / `sanity.config.js`:
 import {createConfig} from 'sanity'
-import {vision} from '@sanity/vision'
+import {visionTool} from '@sanity/vision'
 
 export default createConfig({
   // ...
   plugins: [
-    vision({
+    visionTool({
       // Note: These are both optional
       defaultApiVersion: 'v2021-10-21',
       defaultDataset: 'some-dataset',
@@ -39,9 +39,9 @@ If you only want the tool available in development (eg not in deployed studios),
 ```ts
 // `sanity.config.ts` / `sanity.config.js`:
 import {createConfig, isDev} from 'sanity'
-import {vision} from '@sanity/vision'
+import {visionTool} from '@sanity/vision'
 
-const devOnlyPlugins = [vision()]
+const devOnlyPlugins = [visionTool()]
 
 export default createConfig({
   // ...