docs(readme): use the supported task env field (#2653)

The README task example uses the invalid `envs` field. Replace it with
`env`, matching `docs/config/run.md`, so the example runs and tracks
environment changes for task caching. No source code changed.

Author: SaKaNa-Y

README.md

@@ -79,7 +79,7 @@ export default defineConfig({
     tasks: {
       'generate:icons': {
         command: 'node scripts/generate-icons.js',
-        envs: ['ICON_THEME'],
+        env: ['ICON_THEME'],
       },
     },
   },

packages/cli/README.md

@@ -73,7 +73,7 @@ export default defineConfig({
     tasks: {
       'generate:icons': {
         command: 'node scripts/generate-icons.js',
-        envs: ['ICON_THEME'],
+        env: ['ICON_THEME'],
       },
     },
   },