Update gitbook to use version 3.2.1

[SamyPesse]

Following my answer to #1982, this PR updates GitBook with a fix for anchor links on Firefox.

the URL is retained correctly (Chrome and Firefox), but there still some weird positioning on Firefox, I'll make another PR once we fix this issue as well.

[timdorr]

Is this built-in now? I have that anchorjs plugin to make them work, but if it's not needed anymore, we should drop it.

[SamyPesse]

@timdorr No, the anchorjs adds the anchor icon next to the heading (it will be built in in GitBook v4 or maintained as an official plugin once we complete the switch to React).

This GitBook updates fixes a bug on Firefox when clicking a link containing a hash (#1982).

[timdorr]

Cool. I'll merge this in, as we need to do a rebuild for the new reducer docs anyways.

[SamyPesse]

This is why I believe you should host the documentation on GitBook.com:

• Integrated with GitHub (no need to change the redux code base, expect to remove the docs related scripts from the package.json)
• HTTPS for redux.js.org
• Versioned: Preview the document by branch (redux.js.org/v/mybranch) / tag (redux.js.org/v/1.0.0)
• [Build status when something is breaking the documentation](https://www.gitbook.com/blog/features/github-statuses

Here is a demo setup in 5 min by selecting GitHub while creating a book:

[timdorr]

Cool, we very well may do that. Would it be possible to set up a @Redux org? I already have an account if you need someone to put into the initial set of users.

[markerikson]

@SamyPesse : As a related question: any idea why the current outlining is producing "1.1, 1.2, 1.3", instead of "1, 2, 3"? Would love to get that tweaked.