Upgrade Hugo to 0.55.6

[arvindsv]

[I thought a recent fix in hugo would help with https://github.com//issues/320, but it did not. Since I'd done the upgrade, I decided to just keep it.]

For the upgrade to keep the content the same, I had to make some changes for:

• Block parsing for fenced code blocks with syntax highlighting in lists regression. russross/blackfriday#495
• Code blocks not rendered correctly in lists gohugoio/hugo#2928 (comment)

The changes, after this upgrade are quite small. And, I had to leave those changes there because these were related to bugs in formatting in the old pages. For instance, you'll see issues at the end of https://docs.gocd.org/current/faq/docker_container_ssh_keys.html where formatting is broken.

The diff when this is done:

git reset --hard 1d76c1aa38a88d53b2227ec1995096fe0256d384 # Old master, without this commit.
rm -rf public; yarn run local-build
mv public/ oldpublic/

git reset --hard 163dfd7314d620202c387666113a632b2a5ea801 # This commit.
rm -rf public; yarn run local-build

diff -r -b -B -w oldpublic/ public/

... looks like this:

diff -r -b -B -w oldpublic/faq/admin_out_of_disk_space.html public/faq/admin_out_of_disk_space.html
439,441c440,443
< <li>Change the artifact repository location in the configuration file
< <code>xml 
< &lt;server artifactsDir=&quot;/path/to/new/artifacts&quot;&gt;
---
> 
> <li><p>Change the artifact repository location in the configuration file</p>
> 
> <pre><code>&lt;server artifactsDir=&quot;/path/to/new/artifacts&quot;&gt;
444,445c446,448
< </code></li>
< <li>Start up GoCD server and verify you still have access to old artifacts</li>
---
> </code></pre></li>
> 
> <li><p>Start up GoCD server and verify you still have access to old artifacts</p></li>
diff -r -b -B -w oldpublic/faq/dev_use_current_revision_in_build.html public/faq/dev_use_current_revision_in_build.html
625c626
< <pre><code>deploy-123.txt
---
> <div class="highlight"><pre style="background-color:#f8f8f8;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-text" data-lang="text">deploy-123.txt
627,628c628
< Building pipeline my-app
< </code></pre>
---
> Building pipeline my-app</code></pre></div>
662c666
< <pre><code>deploy-123.txt
---
> <div class="highlight"><pre style="background-color:#f8f8f8;-moz-tab-size:4;-o-tab-size:4;tab-size:4"><code class="language-text" data-lang="text">deploy-123.txt
665,666c669
< Configuration version: 59cab75ccf231b9e338c96cff0f4adad5cb7d335
< </code></pre>
---
> Configuration version: 59cab75ccf231b9e338c96cff0f4adad5cb7d335</code></pre></div>
diff -r -b -B -w oldpublic/faq/docker_container_ssh_keys.html public/faq/docker_container_ssh_keys.html
399,401c400,402
< <li>The ownership and permissions of files in <code>/home/go/.ssh</code> is:
< <code>bash
< -rw-------    1 go       go            3243 Jan 11 07:00 id_rsa
---
> <li><p>The ownership and permissions of files in <code>/home/go/.ssh</code> is:</p>
> 
> <pre><code>-rw-------    1 go       go            3243 Jan 11 07:00 id_rsa
404c405
< </code></li>
---
> </code></pre></li>
diff -r -b -B -w oldpublic/index.html public/index.html
7c8
< 	<meta name="generator" content="Hugo 0.53" />
---
> 	<meta name="generator" content="Hugo 0.55.6" />
diff -r -b -B -w oldpublic/sitemap.xml public/sitemap.xml
6a7
>     <priority>0</priority>
10a12
>     <priority>0</priority>

[arvindsv]

It's not worth reviewing this change much, since the final content before and after is very similar. I'll merge it if the build succeeds.

[ketan]

I've reverted this change. The new markdown is harder to read (and understand why the blocks are written the way they are)