docs(operators): add documentation for single

src/operator-docs/filtering/single.ts

@@ -1,6 +1,40 @@
 import { OperatorDoc } from '../operator.model';
 
 export const single: OperatorDoc = {
-  'name': 'single',
-  'operatorType': 'filtering'
+  name: 'single',
+  operatorType: 'filtering',
+  signature: 'public single(predicate: Function): Observable<T>',
+  parameters: [
+    {
+      name: 'predicate',
+      type: 'Function',
+      attribute: '',
+      description:
+        'A predicate function to evaluate items emitted by the source Observable.'
+    }
+  ],
+  marbleUrl: 'http://reactivex.io/rxjs/img/single.png',
+  shortDescription: {
+    description: `Returns an Observable that emits the single item emitted by the source Observable
+       that matches a specified predicate, if that Observable emits one such item.
+       If the source Observable emits more than one such item or no such items, notify of an IllegalArgumentException
+       or NoSuchElementException respectively.`
+  },
+  examples: [
+    {
+      name: 'Emit first number passing predicate',
+      code: `
+      //emit (1,2,3,4,5)
+      const source = Rx.Observable.from([1, 2, 3, 4, 5]);
+      //emit one item that matches predicate
+      const example = source.single(val => val === 4);
+      //output: 4
+      const subscribe = example.subscribe(val => console.log(val));
+      `,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/solecibuza/embed?js,console'
+      }
+    }
+  ]
 };