Héctor Ramos db621b03b6 Improve social share previews, expand author bylines ...

Summary:
Several blog and sharing improvements are included in this update.

* A larger default preview image is used when a blog post or doc is shared on social media as recommended by [best practices](https://developers.facebook.com/docs/sharing/best-practices#images).
* Follow other Facebook Sharing best practices such as associating the site with a Facebook Page (React) and a Page Admin (121800083 is my fbid, and I am an admin for the React page).
* If the shared blog post contains a hero image, use it as a share preview image.
* Use actual doc content instead of generic site description when sharing docs.
* Update existing hero images to use the larger recommended size.
* Add titles to each author's byline.
* Add author's avatar to their byline.
* Add Twitter Card support.
* Link to individual blog posts from the title and hero image in the blog index.

Old metadata tags (blog post):
```
<meta property="og:title" content="Toward Better Documentation – React Native | A framework for building native
Closes https://github.com/facebook/react-native/pull/9648

Differential Revision: D3790332

Pulled By: hramos

fbshipit-source-id: 4f284c6440482df8a42a2b8467ccf56b1fd725d1

2016-08-29 23:13:43 -07:00

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img

Improve social share previews, expand author bylines

2016-08-29 23:13:43 -07:00

2016-03-24-introducing-hot-reloading.md

Improve social share previews, expand author bylines

2016-08-29 23:13:43 -07:00

2016-07-06-toward-better-documentation.md

Improve social share previews, expand author bylines

2016-08-29 23:13:43 -07:00

2016-08-12-react-native-meetup-san-francisco.md

Improve social share previews, expand author bylines

2016-08-29 23:13:43 -07:00

2016-08-19-right-to-left-support-for-react-native-apps.md

Improve social share previews, expand author bylines

2016-08-29 23:13:43 -07:00