Move two column layout into fences using markdown-it-container.

[muffinresearch]

Today there is code like this:

<!-- END: Single Column Body Module -->

<!-- Two Column Body Module -->

{% capture col_1_content %}

Help users separate their browser activities with [Contextual Identities](https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/contextualIdentities) a.k.a. Containers. Give groups of tabs their own local browser storage: cookie store and local data in localStorage and indexedDB. This keeps details such as site preferences, signed in sessions, and ad tracking data private to the tabs.

{% endcapture %}

{% capture col_2_content %}

![Containers-screenshot](/assets/img/documentation/develop/containers.png "A screenshot of a container dropdown menu, which includes Personal, Work, Banking, and Shopping containers, and the option to Manage Containers")

{% endcapture %}
{% include modules/two-column.liquid
	col_1: col_1_content
	col_2: col_2_content
%}

<!-- END: Two Column Body Module -->

This could be simplified into some markdown extensions instead. This could look something like this:

::: 2-column-layout
:::: column-1
Help users separate their browser activities with [Contextual Identities](https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/contextualIdentities) a.k.a. Containers. Give groups of tabs their own local browser storage: cookie store and local data in localStorage and indexedDB. This keeps details such as site preferences, signed in sessions, and ad tracking data private to the tabs.
::::

:::: column-2
![Containers-screenshot](/assets/img/documentation/develop/containers.png "A screenshot of a container dropdown menu, which includes Personal, Work, Banking, and Shopping containers, and the option to Manage Containers")
::::
:::