Update quickstart and new user workflows

[dwelsch-esi]

Overview

Rename to "Quick start" (two words). Add a "Prerequisites" section and revise the "What's next" section to focus on two separate paths, Development and Operations. Write separate "Getting started" workflows for Developer and Operator users. For the developer path, link to the "Set up a local cluster" page rather than the install page.

Audience: All

Type: Task

The existing documentation might contain helpful source material that you can pull into this doc change. See recommendations for the existing (at the time of the CNCF tech doc analysis) etcd technical documentation pages:
https://github.com/cncf/techdocs/blob/main/assessments/0010-etcd/etcd-implementation.md/#general-reorganization

🎤 Context

This issue tracks recommended changes resulting from an analysis of the etcd documentation commissioned by CNCF. The analysis and supporting documents are here: https://github.com/cncf/techdocs/tree/main/assessments/0010-etcd/

✌️ Possible Implementation

Related material in the current doc:

• https://github.com/etcd-io/website/blob/main/content/en/docs/v3.5/quickstart.md