Adds a new docs website, built with Gatsby JS, to replace the old Jekyll site. Source code for the new site lives in /www (although markdown and YML data still comes from the legacy /docs folder).
Changes to either markdown or website source code can be previewed on Netlify. The react-js bot should automatically add comments to each PR with preview links. (This preview is generated by running the newly-added yarn build:docs command in the root package.json.)
The majority of the changes in this PR are contained within the new /www directory. However some minor modifications have been made to existing content in the /docs directory:
* Modified frontmatter author block to always be an array
* Small markdown formatting tweaks
* 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