docs(operators): add documentation for pluck

src/operator-docs/transformation/pluck.ts

@@ -1,6 +1,58 @@
 import { OperatorDoc } from '../operator.model';
 
 export const pluck: OperatorDoc = {
-  'name': 'pluck',
-  'operatorType': 'transformation'
+  name: 'pluck',
+  operatorType: 'transformation',
+  signature: 'public pluck(properties: ...string): Observable',
+  marbleUrl: 'http://reactivex.io/rxjs/img/pluck.png',
+  parameters: [
+    {
+      name: 'properties',
+      type: '...string',
+      attribute: '',
+      description: `
+        The nested properties to 'pluck' from each source value (an object).
+      `
+    }
+  ],
+  shortDescription: {
+    description:
+      'Maps each source value (an object) to its specified nested property.',
+    extras: [
+      {
+        type: 'Tip',
+        text: `
+          Like <a href="#/operators/map" class="markdown-code">map</a>, but meant
+          only for picking one of the nested properties of every emitted object.
+        `
+      }
+    ]
+  },
+  walkthrough: {
+    description: `
+      <p>
+        Given a list of strings describing a path to an object property, retrieves
+        the value of a specified nested property from all values in the source Observable.
+        If a property can't be resolved, it will return <span class="markdown-code">undefined</span>
+        for that value.
+      </p>
+    `
+  },
+  examples: [
+    {
+      name:
+        'Map every every click to the tagName of the clicked target element',
+      code: `
+        const clicks = Rx.Observable.fromEvent(document, 'click');
+        const tagNames = clicks.pluck('target', 'tagName');
+        tagNames.subscribe(x => console.log(x));
+      `,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/vucuca/embed?js,console,output'
+      }
+    }
+  ],
+  relatedOperators: ['map'],
+  additionalResources: []
 };