style: Unified style (#636)

Author: FAKER-A

src/guide/migration/custom-directives.md

@@ -49,7 +49,7 @@ In Vue 3, however, we’ve created a more cohesive API for custom directives. As
 - **beforeUpdate**: new! this is called before the element itself is updated, much like the component lifecycle hooks.
 - update → removed! There were too many similarities to updated, so this is redundant. Please use updated instead.
 - componentUpdated → **updated**
-- **beforeUnmount** new! similar to component lifecycle hooks, this will be called right before an element is unmounted.
+- **beforeUnmount**: new! similar to component lifecycle hooks, this will be called right before an element is unmounted.
 - unbind -> **unmounted**
 
 The final API is as follows: