Added documentation

docs/content-services/directives/node-counter.directive.md

@@ -0,0 +1,28 @@
+---
+Title: Node Counter directive
+Added: v4.4.0
+Status: Active
+Last reviewed: 2021-04-15
+---
+
+# [Node Counter directive](../../../lib/content-services/src/lib/directives/node-counter.directive.ts "Defined in node-counter.directive.ts")
+
+Appends a counter to an element.
+
+## Basic Usage
+
+```html
+<adf-toolbar>
+    <adf-toolbar-title [adf-node-counter]="getSelectedCount()">
+        ...
+    </adf-toolbar-title>
+</adf-toolbar>
+```
+
+## Class members
+
+### Properties
+
+| Name | Type | Default value | Description |
+| ---- | ---- | ------------- | ----------- |
+| counter | `number` |  | Number of nodes selected. |