Create a better, more flexible jumbotron/hero

[celestehorgan]

Use case

Most CNCF websites follow an existing pattern for headers: see Longhorn, Prometheus, etc.

Create a Hero/Jumbotron-like layout partial or shortcode. It should be able to read in info from a YAML file or similar and offer some level of flexibility with placement, colors, background image, etc.

In general we expect that many projects will want to override the 'default', but it's still useful to have a fully featured one!