Write a Getting Started page

[dwelsch-esi]

The Quickstart tutorial is useful, but it doesn't fully orient new users. A
getting started page would help, with meta information about what to expect
and where to go on the documentation site.

Overview

Audience: New users

Type: Instructional

Context

This issue tracks recommended changes resulting from an analysis of the Knative
documentation commissioned by CNCF. The analysis and supporting documents are
here: https://github.com/cncf/techdocs/tree/main/analyses under 0015-knative.

Possible Implementation

Related material in the current doc:

• https://github.com/knative/
• https://knative.dev/docs/getting-started/

Suggested changes:

Add a "Getting Started" page at the top level of the documentation. This page
should map a reader's user role and goals to content that helps them install,
evaluate, or learn about the product, depending on their goal. For exmaple,
direct new users to the Quickstart tutorial, evaluators or potential buyers to
the conceptual overview, and so on.

See, for example, getting started pages for:

• [Kubernetes]
• [The Update Framework]
  (a little unusual because it's a specification, not a software product)
• [Python] (a kitchen-sink approach, to be sure)