Updated README with expandable table of content.

[claesgill]

📑 Summary

Updated README with expandable table of content.
Aims for more easily finding content in the main README.md.

📏 Design Decisions

Not relevant

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 🔖 targeted develop branch

[netlify]

✅ Deploy Preview for mermaid-js ready!

Name	Link
🔨 Latest commit	3389ecd
🔍 Latest deploy log	https://app.netlify.com/sites/mermaid-js/deploys/653196f5f5e6b600085bb41a
😎 Deploy Preview	https://deploy-preview-4961--mermaid-js.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 configuration.

[codecov]

Codecov Report

Merging #4961 (3389ecd) into develop (33a5fc4) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #4961   +/-   ##
========================================
  Coverage    79.37%   79.37%           
========================================
  Files          164      164           
  Lines        13815    13815           
  Branches       693      693           
========================================
  Hits         10966    10966           
  Misses        2700     2700           
  Partials       149      149           

Flag	Coverage Δ
e2e	85.23% <ø> (ø)
unit	42.94% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[mermaid-bot]

@claesgill, Thank you for the contribution!
You are now eligible for a year of Premium account on MermaidChart.
Sign up with your GitHub account to activate.