docs: improve example to better clarify rule (#1985)

Author: mesqueeb

Diff for: docs/rules/define-emits-declaration.md

@@ -25,6 +25,12 @@ const emit = defineEmits<{
   (e: 'update', value: string): void
 }>()
 
+/* ✗ BAD */
+const emit = defineEmits({
+  change: (id) => typeof id == 'number',
+  update: (value) => typeof value == 'string'
+})
+
 /* ✗ BAD */
 const emit = defineEmits(['change', 'update'])
 </script>
@@ -53,6 +59,12 @@ const emit = defineEmits<{
   (e: 'update', value: string): void
 }>()
 
+/* ✓ GOOD */
+const emit = defineEmits({
+  change: (id) => typeof id == 'number',
+  update: (value) => typeof value == 'string'
+})
+
 /* ✓ GOOD */
 const emit = defineEmits(['change', 'update'])
 </script>