chore: fix typo (vuejs#339)

Author: dsseng

packages/runtime-core/README.md

@@ -10,7 +10,7 @@ For full exposed APIs, see `src/index.ts`. You can also run `yarn build runtime-
 import { createRenderer, createAppAPI } from '@vue/runtime-core'
 
 const { render, createApp } = createRenderer({
-  pathcProp,
+  patchProp,
   insert,
   remove,
   createElement,