docs(operators): add documentation for operator from

src/operator-docs/creation/from.ts

@@ -1,6 +1,91 @@
 import { OperatorDoc } from '../operator.model';
 
 export const from: OperatorDoc = {
-  'name': 'from',
-  'operatorType': 'creation'
+  name: 'from',
+  operatorType: 'creation',
+  signature: `from(ish: ArrayLike | ObservableInput, scheduler: Scheduler): Observable`,
+  parameters: [
+    {
+      name: 'ish',
+      type: 'ArrayLike | ObservableInput',
+      attribute: '',
+      description: `A subscribable object, a Promise, an  Observable-like, an Array, an
+	  iterable or an array-like object to be converted.`
+    },
+    {
+      name: 'scheduler',
+      type: 'Scheduler',
+      attribute: 'optional',
+      description: `The scheduler on which to schedule the emissions of values.`
+    }
+  ],
+  marbleUrl: 'http://reactivex.io/rxjs/img/from.png',
+  shortDescription: {
+    description: `Creates an Observable from an Array, an array-like object, a Promise, an
+    iterable object, or an Observable-like object.
+    <span class="informal">Converts almost anything to an Observable.</span>`
+  },
+  walkthrough: {
+    description: `Converts various other objects and data types into Observables. <span class="markdown-code">from</span>
+    converts a Promise or an array-like or an
+    <a href ='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#iterable' target='_blank'>iterable</a>
+    object into an Observable that emits the items in that promise or array or
+    iterable. A String, in this context, is treated as an array of characters.
+    Observable-like objects (contains a function named with the ES2015 Symbol
+    for Observable) can also be converted through this operator.
+   `
+  },
+  examples: [
+    {
+      name: 'Converts an array to an Observable',
+      code: `
+      const array = [10, 20, 30];
+      const result = Rx.Observable.from(array);
+      result.subscribe(x => console.log(x));
+
+      // Results in the following:
+      // 10 20 30`,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/qodocay/embed?js,console'
+      }
+    },
+    {
+      name: 'Convert an infinite iterable (from a generator) to an Observable',
+      code: `
+      function* generateDoubles(seed) {
+        let i = seed;
+        while (true) {
+          yield i;
+          i = 2 * i; // double it
+        }
+      }
+      const iterator = generateDoubles(3);
+      const result = Rx.Observable.from(iterator).take(10);
+      result.subscribe(x => console.log(x));
+      // Results in the following:
+      // 3 6 12 24 48 96 192 384 768 1536`,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/kidevan/embed?js,console'
+      }
+    },
+    {
+      name:
+        'Using <span class="markdown-code">from</span> with async scheduler',
+      code: `
+      console.log('start');
+      const array = [10, 20, 30];
+      const result = Rx.Observable.from(array, Rx.Scheduler.async);
+      result.subscribe(x => console.log(x));
+      console.log('end');
+      // Results in the following:
+      // start end 10 20 30`,
+      externalLink: {
+        platform: 'JSBin',
+        url: 'http://jsbin.com/xunesam/embed?js,console'
+      }
+    }
+  ],
+  relatedOperators: ['create', 'fromEvent', 'fromEventPattern', 'fromPromise']
 };