update v-ref doc

Author: yyx990803

source/api/directives.md

@@ -190,7 +190,7 @@ Compile this element as a child ViewModel with a registered component constructo
 
 ### v-ref
 
-Only respected when used in combination with `v-component`, `v-with` or `v-repeat`. The ViewModel will be accessible in its parent's `$` object, e.g. `parent.$[id]`. When used with `v-repeat`, the value will be an Array containing the child ViewModel instances corresponding to the Array they are bound to. For examples see [Accessing Child Components](/guide/composition.html#Accessing_Child_Components).
+Only respected when used in combination with directives that create child components: `v-component`, `v-view`, `v-if` or `v-repeat`. The ViewModel will be accessible in its parent's `$` object, e.g. `parent.$[id]`. When used with `v-repeat`, the value will be an Array containing the child ViewModel instances corresponding to the Array they are bound to. For examples see [Accessing Child Components](/guide/composition.html#Accessing_Child_Components).
 
 ### v-partial