Add guide on integrating with non-react code (#9316)

* Add guide on integrating with non-react code

* Capitalize guide title

* Make links to other docs relative

* Rephrase 'What it does do'

* Remove experimental syntax

* Capitalize Backbone

* Remove empty lifecycle method in generic jQuery example

* Use shouldComponentUpdate() not componentWillUpdate()

* Prefer single quotes

* Add cleanup to generic jQuery example

* Capitalize React

* Generalize the section on Backbone Views

* Generalize the section on Backbone Models, a little

* Add introduction

* Adjust wording

* Simplify ref callbacks

* Fix typo in generic jQuery example

* Fix typos in Backbone models in React components

* Fix more typos in Backbone models in React components

* Add generic section on integrating with other view libraries

* Stress the benefits of an unchanging React element

* Small changes to introduction

* Add missing semicolon

* Revise generic jQuery wrapper section

Moved the section on using empty elements to prevent conflicts above the
code example and added brief introduction to that example.

* Add usage example for Chosen wrapper

* Prevent Chosen wrapper from updating

* Note that sharing the DOM with plugins is not recommended

* Mention how React is used at Facebook

* Mention React event system in template rendering section

* Remove destructuring from function parameters

* Do not name React components Component

* Elaborate on unmountComponentAtNode()

* Mention preference for unidirectional data flow

* Rename backboneModelAdapter

* Replace rest syntax

* Respond to updated model in connectToBackboneModel

* Rewrite connectToBackboneModel example

* Rework connectToBackboneModel example

* Misc changes

* Misc changes

* Change wording

* Tweak some parts

(cherry picked from commit 1816d06)

Author: wacii

docs/_data/nav_docs.yml

@@ -50,6 +50,8 @@
       title: Web Components
     - id: higher-order-components
       title: Higher-Order Components
+    - id: integrating-with-other-libraries
+      title: Integrating with Other Libraries
 - title: Reference
   items:
     - id: react-api