[ADF-1549] Added files for Core library (#2345)

* [ADF-1549] Added files for Core library

* [ADF-1549] Updated md files following checks

docs/context-menu.directive.md

@@ -0,0 +1,50 @@
+# Context Menu directive
+
+<!-- markdown-toc start - Don't edit this section.  npm run toc to generate it-->
+
+<!-- toc -->
+
+- [Basic Usage](#basic-usage)
+- [Details](#details)
+
+<!-- tocstop -->
+
+<!-- markdown-toc end -->
+
+## Basic Usage
+
+```html
+<my-component [context-menu]="menuItems"></my-component>
+<context-menu-holder></context-menu-holder>
+```
+
+```ts
+@Component({
+    selector: 'my-component'
+})
+export class MyComponent implements OnInit {
+
+    menuItems: any[];
+
+    constructor() {
+        this.menuItems = [
+            { title: 'Item 1', subject: new Subject() },
+            { title: 'Item 2', subject: new Subject() },
+            { title: 'Item 3', subject: new Subject() }
+        ];
+    }
+
+    ngOnInit() {
+        this.menuItems.forEach(l => l.subject.subscribe(item => this.commandCallback(item)));
+    }
+
+    commandCallback(item) {
+        alert(`Executing ${item.title} command.`);
+    }
+
+}
+```
+
+## Details
+
+See **Demo Shell** or **DocumentList** implementation for more details and use cases.