Plugins: Add `chai-jq` plugin to docs.

## Actual PR - a new plugin

Adds the [`chai-jq`](https://github.com/FormidableLabs/chai-jq) plugin to the list. The aim of the plugin is an API that doesn't override existing Chai assertion methods / properties.

## Other Notes
As a side note, on my machine at least, running `make` in this repo gives me the following uncommited files:

```
$ make
$ git status
# On branch add-chai-jq-plugin
# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#	modified:   out/api/assert/index.html
#	modified:   out/api/bdd/index.html
#	modified:   out/api/index.html
#	modified:   out/api/plugins/index.html
#	modified:   out/api/test/index.html
#	modified:   out/guide/helpers/index.html
#	modified:   out/guide/index.html
#	modified:   out/guide/installation/index.html
#	modified:   out/guide/plugins/index.html
#	modified:   out/guide/resources/index.html
#	modified:   out/guide/styles/index.html
#
no changes added to commit (use "git add" and/or "git commit -a")
```

I think the markdown library has bumped due to perhaps a loose dependency, and I see diffs like:

```
diff --git a/out/api/assert/index.html b/out/api/assert/index.html
index 0a45f49..97dfa1f 100644
--- a/out/api/assert/index.html
+++ b/out/api/assert/index.html
@@ -64,14 +64,14 @@
         <div class="documentation">
           <div class="wrap">
             <div class="rendered">
-              <article><h1>Assert</h1>
+              <article><h1 id="assert">Assert</h1>
 <p>The <code>assert</code> style is very similar to node.js&#39; included assert module, which a bit of extra
 sugar. Of the three style options, <code>assert</code> is the only one that is not chainable. Check out 
 the <a href="/guide/comparison">Style Guide</a> for a comparison.</p>
-<h2>API Reference</h2>
+<h2 id="api-reference">API Reference</h2>
 </article>
...
```

I have *not* checked in those diffs in this PR, saving them for whomever knows best on the subject ;)