feat: sub-categories in sidebar.json

[WillBrock]

Motivation

Close #410
Close #948

Some users would like to be able to specify sub categories in the sidebar as discussed in #410.

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

Added unit tests for the functions that were modified and visually verified existing sidebars function the same as well as the new sub categories.

Example sidebars:

{
  "docs": {
    "First Category": {
      "Sub Cat One" : ["doc2", "doc3"],
      "Sub Cat Two" : ["doc4", "doc5"]
    },
    "Second Category" : ["doc8"]
  }
}

{
  "docs": {
    "First Category": {
     // Empty key will display no header
      "" : ["doc1"],
      "Sub Cat One" : ["doc2", "doc3"],
      "Sub Cat Two" : ["doc4", "doc5"]
    },
    "Second Category" : ["doc8"]
  }
}

First attempt at implementing this, let me know if some things should be changed. I changed a couple of the functions around to make them easier to write tests against. In the future we could add tests to the rest of the functions in readMetadata.js as well.

Note: We could maybe do some type of accordion for the sub categories if wanted.

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[endiliey]

Thanks for the PR and sorry for getting back so late. This is quite a huge change so it will take a while for review.

Update:
https://docusaurus.io/blog/2018/09/11/Towards-Docusaurus-2

With the major re-write and re-architecture for Docusaurus v2, we will be less likely to accept new features/major changes on Docusaurus 1.

[ricardokdz]

+1

[markerikson]

Hi. I see the comments about "less likely to accept v1 PRs". I'm a Redux maintainer, and we're currently investigating switching our docs site at https://redux.js.org to Docusaurus. We've already set it up for the new React-Redux docs page at https://react-redux.js.org .

The Redux docs have multiple levels of nesting in some places. While we're planning on restructuring the docs content itself in the near future, it would be really helpful if we could keep the existing structure for now as part of a switch to Docusaurus.

Would it be possible to get this PR merged in soon (like, the next few days)?

[yangshun]

Hey @markerikson, that's cool! We'd definitely consider that. I'll look into this further tonight. May I know the reason that you're migrating the Redux docs over from Gitbook to Docusaurus? As far as I can tell, the current Redux docs look great!

[markerikson]

@yangshun : sure, there's several reasons:

• We're working on completely rewriting the React-Redux docs ( Rewrite React-Redux docs completely reduxjs/react-redux#1001 ), and are also looking at heavily revamping the main Redux docs ( General docs review, consideration, and improvements reduxjs/redux#2590 )
• Since React-Redux didn't have any published docs yet, only the Markdown files in the repo, we just tried setting up Docusaurus for it and it looks good so far ( Investigate alternative docs publishing solutions reduxjs/react-redux#1031 )
• Meanwhile, I'm not terribly happy with the Gitbook publishing flow and some other bugs and limitations we've seen ( Investigate alternative docs publishing solutions reduxjs/redux#3161 ), so I'm asking for other options. Since we just set up Docusaurus for React-Redux, it makes sense to use it for Redux as well.

[endiliey]

[yangshun]

@markerikson it's been shipped! Many thanks to @endiliey for making it happen.

We'll release v1.4.1 release very soon (within the next few days) and Redux would be able to use it.