docs: update defineCustomElement

Author: rudyxu1102

active-rfcs/0000-infer-attrs.md

@@ -10,7 +10,7 @@ I already published an npm package named [vue-ts-utils](https://github.com/rudy-
 
 # Basic example
 
-## Using `defineComponent` directly
+## Using `defineComponent`
 [TS Playground](https://www.typescriptlang.org/play?jsx=1#code/JYWwDg9gTgLgBAbzgEwKYDNgDtUGELgQ5bwC+c6UBcA5AG4CuqAtDAM7MMzAA2bNAWABQwgMZE28fODgBeFBmx4CkYjAAUCYXDhgqYNgC5E2nRQgRjAZRhRsAcwA0p0s6E6oqLGijqAlIikwq6IcACGMLZGgeFsoQBGYVDGWAwg8ahQcOSkfsJiEvDiMvIAPNJg5hCyCDQAjDTkiVA1deQA9AB8wkA)
 ```tsx
 const Comp = defineComponent({
@@ -48,6 +48,21 @@ return { attrs, useAttrs, ref }
 
 </details>
 
+
+## Using `defineCustomElement`
+```tsx
+const Comp = defineCustomElement({
+  props: {
+    foo: String
+  },
+  render() {
+    // number
+    console.log(this.$attrs.bar)
+  }
+}, { attrs: {} as { bar: number } })
+
+```
+
 # Motivation
 This proposal is mainly to infer `attrs` using `defineComponent`.
 
@@ -84,6 +99,8 @@ return { attrs, useAttrs, ref }
 }, { attrs: {} as { foo: number }})"
 ```
 
+## `defineCustomElement`
+The type inferrence of `defineCustomElement` is the same as `defineComponent`.
 
 
 # Unresolved questions