docs: clarify the usage of toRefs and toRef for optional props

vuejs/docs@a502ebe#diff-3ace6f6da65a6723abafa4cd506303a9202b768e52434e78764dd1dae74db376
vuejs-jp · kazupon · Apr 26, 2021 · Apr 26, 2021 · Apr 26, 2021 · Apr 26, 2021
commit 3f2381b535a548a51e95a4fc6ea6689c5efd4a48
diff --git a/src/guide/composition-api-introduction.md b/src/guide/composition-api-introduction.md
@@ -18,7 +18,10 @@ Vue コンポーネントを作成するとその機能と結合されたイン
 export default {
   components: { RepositoriesFilters, RepositoriesSortBy, RepositoriesList },
   props: {
-    user: { type: String }
+    user: {
+      type: String,
+      required: true
+    }
   },
   data () {
     return {
@@ -86,7 +89,10 @@ export default {
 export default {
   components: { RepositoriesFilters, RepositoriesSortBy, RepositoriesList },
   props: {
-    user: { type: String }
+    user: {
+      type: String,
+      required: true
+    }
   },
   setup(props) {
     console.log(props) // { user: '' }
@@ -192,7 +198,10 @@ import { ref } from 'vue'
 export default {
   components: { RepositoriesFilters, RepositoriesSortBy, RepositoriesList },
   props: {
-    user: { type: String }
+    user: {
+      type: String,
+      required: true
+    }
   },
   setup (props) {
     const repositories = ref([])
@@ -449,7 +458,10 @@ import { toRefs } from 'vue'
 export default {
   components: { RepositoriesFilters, RepositoriesSortBy, RepositoriesList },
   props: {
-    user: { type: String }
+    user: {
+      type: String,
+      required: true
+    }
   },
   setup (props) {
     const { user } = toRefs(props)
@@ -495,7 +507,10 @@ import useRepositoryFilters from '@/composables/useRepositoryFilters'
 export default {
   components: { RepositoriesFilters, RepositoriesSortBy, RepositoriesList },
   props: {
-    user: { type: String }
+    user: {
+      type: String,
+      required: true
+    }
   },
   setup(props) {
     const { user } = toRefs(props)