fix: mentioned arguments in all directive hooks

Close #1861

Author: NataliaTepluhina

src/guide/reusability/custom-directives.md

@@ -115,19 +115,19 @@ const myDirective = {
     // see below for details on arguments
   },
   // called right before the element is inserted into the DOM.
-  beforeMount() {},
+  beforeMount(el, binding, vnode, prevVnode) {},
   // called when the bound element's parent component
   // and all its children are mounted.
-  mounted() {},
+  mounted(el, binding, vnode, prevVnode) {},
   // called before the parent component is updated
-  beforeUpdate() {},
+  beforeUpdate(el, binding, vnode, prevVnode) {},
   // called after the parent component and
   // all of its children have updated
-  updated() {},
+  updated(el, binding, vnode, prevVnode) {},
   // called before the parent component is unmounted
-  beforeUnmount() {},
+  beforeUnmount(el, binding, vnode, prevVnode) {},
   // called when the parent component is unmounted
-  unmounted() {}
+  unmounted(el, binding, vnode, prevVnode) {}
 }
 ```