Add third party packages section to document

[Ailrun]

What: Documents for third party packages

Why: To support and encourage third party package authors.

How: Rename "Packages" section into "Official Packages" and add "Third Party Packages" section.

Checklist:

• Documentation
• [N/A] Tests
• [N/A] Code complete

Resolves #638.

[Ailrun]

What is that weird error? Why couldn't it find a handlebar?
@mitchellhamilton Do you know what the error means? Could you let me know?

[emmatown]

@Ailrun It's saying that the language handlebars hasn't been imported.
Add this here

require('prismjs/components/prism-handlebars')

[Ailrun]

@mitchellhamilton Ah, his document use handlebars... I missed that part. I will fix that.

[emmatown]

I've been thinking about this and I'm not sure if it's a good idea because if we add the documentation for one package then we have to add the documentation for every package that wants it and it's effectively saying we recommend whatever packages that are there.

I think a better solution is to add a top level Community page, add it to the links at the top and have the contents be from emotion-js/awesome-emotion which I just created, similar to https://www.styled-components.com/ecosystem.

[Ailrun]

@mitchellhamilton Wow, awesome opinion! Thank you for making that repository. However, I wish that there is a link to your repository from our site. Is it OK for you?

[emmatown]

I was thinking, instead of linking to it, embed the contents of it in the site.

[Ailrun]

@mitchellhamilton All contents? Just like styled component did?

[Ailrun]

Close this in favor of #720.