docs: add diagrams page to 2.2.0 sidebar

[homotechsual]

Adds the diagrams page to the sidebar for 2.2.0.

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

Test Plan

Test links

Deploy preview: https://deploy-preview-_____--docusaurus-2.netlify.app/

Related issues/PRs

[netlify]

✅ [V2]

Built without sensitive environment variables

Name	Link
🔨 Latest commit	79bd4d4
🔍 Latest deploy log	https://app.netlify.com/sites/docusaurus-2/deploys/639757c9941a42000f934d85
😎 Deploy Preview	https://deploy-preview-8431--docusaurus-2.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟢 91	🟢 97	🟢 100	🟢 100	🟢 90	Report
/docs/installation	🟠 73	🟢 100	🟢 100	🟢 100	🟢 90	Report

[Josh-Cena]

Great catch :)