id in category selector

src/components/show_category.vue

@@ -27,6 +27,7 @@
 		<summary><h2>Show Category</h2></summary>
 		<select @change="change">
 			<option v-for="category in categories" v-bind:value="category.id">
+				{{category.id}}.
 				{{category.instrument}}
 				:
 				{{category.category}}