Add Hugo front matter to docs

[adambkaplan]

The community wants to keep docs close to the code, and implement a sync process to add the documentation to the shipwright.io website. See shipwright-io/website#29.

Today the sync is a manual process that involves me manually copying content from this repository, then applying the Hugo front matter that organizes the presentation of articles in the table of contents. As a first step at improving this process, the front matter should be added to the docs in this repository. The articles that are copied over (with their front matter) can be found here. The corresponding markdown can be found here.

Most Hugo documentation suggests that the front matter needs to be visible in the Markdown file, but this is not the case. The front matter can be inserted in an HTML comment, and Hugo will read it just fine.

/kind documentation