[Docs] Improve visibility of Tab Menus (for tabbed content)

[leecalcote]

Current State

Example tabbed content - https://docs.layer5.io/cloud/reference/default-permissions/

Desired State

---

Contributor Guide and Resources

• 📚 Instructions for contributing to documentation
  • Layer5 documentation site and source
• 🎨 Wireframes and designs for Layer5 site in Figma (open invite)
• 🙋🏾🙋🏼 Questions: Layer5 Discussion Forum and Layer5 Community Slack

[Sumitsh28]

@leecalcote I have made a slight change to the background color. Let me know if it looks better than before.

[leecalcote]

@Sumitsh28 thank you. This looks pretty great to me. 👍