Add installation docs

[guineveresaenger]

Part of pulumi/home#3598

Generates a single index.md file with relevant content.

• Add automation
• Skip secrets disclaimer section and make docs

[github-actions[bot]]

Does the PR have any schema changes?

Looking good! No breaking changes found. No new resources/functions.

Maintainer note: consult the runbook for dealing with any breaking changes.

[pulumi-bot]

This PR has been shipped in release v5.0.8.