update reference

docs/reference/components/placeholder.md

@@ -8,12 +8,12 @@ import { Placeholder } from 'slate'
 A simple component that adds a placeholder to a node. It encapsulates all of the Slate-related logic that determines when to render the placeholder, so you don't have to think about it.
 
 - [Properties](#properties)
-  - [`children`](#children-any)
-  - [`className`](#className-string)
-  - [`node`](#node-node)
-  - [`parent`](#parent-node)
-  - [`state`](#state-state)
-  - [`style`](#style-object)
+  - [`children`](#children)
+  - [`className`](#className)
+  - [`node`](#node)
+  - [`parent`](#parent)
+  - [`state`](#state)
+  - [`style`](#style)
 
 
 ## Properties
@@ -30,26 +30,32 @@ A simple component that adds a placeholder to a node. It encapsulates all of the
 </Placeholder>
 ```
 
-#### `children: Any`
+### `children`
+`Any`
 
 React child elements to render inside the placeholder `<span>` element.
 
-#### `className: String`
+### `className`
+`String`
 
 An optional class name string to add to the placeholder `<span>` element.
 
-#### `node: Node`
+### `node
+`Node`
 
 The node to render the placeholder element on top of. The placeholder is positioned absolutely, covering the entire node.
 
-#### `parent: Node`
+### `parent
+`Node`
 
 The node to check for non-empty content, to determine whether the placeholder should be shown or not.
 
-#### `state: State`
+### `state
+`State`
 
 The current state of the editor.
 
-#### `style: Object`
+### `style
+`Object`
 
 An optional dictionary of styles to pass to the placeholder `<span>` element.