message: docs: fix directive guide md format
diff: @@ -65,6 +65,7 @@ export default {
  };
  </script>
  ```
  +
  ### persist
  You can use `.persist` modifier to keep the field (and its possible error(s)) in memory when the field is unmount/removed from the DOM (e.g. in a `v-if` block).
  @@ -94,11 +95,13 @@ export default {
  ::: tip
  You can force it to disappear completely by changing the `persist` property in the field object:
  +
  ```js
  this.$validator.fields.find({name: 'email'}).persist = false;
  this.diplayField = false;
  // The field instance and its errors will also disappear from the memory in the next tick
  ```
  +
  :::
  ### continues
  