Limit Mermaid JavaScript dependency to the GitLab Handbook

Problem to solve

The Mermaid JavaScript dependency is included across all of about.gitlab.com adding a very large amount of JS payload to pages that don't need it.

Proposal

As a first step we should limit the include to the Handbook only. Future iterations can look at limiting it to only specific pages that actually need it.

Consideration

There are pages outside of the Handbook that makes use of mermaid diagrams and we need to ensure to include it on those pages as well:

• /source/direction/verify/runner/index.html.md
• /sites/blog/source/blog/blog-posts/2020-03-30-how-to-exploit-parser-differentials.html.md.erb
• /source/company/strategy/index.html.md
• /source/direction/growth/index.html.md
• /source/direction/monitor/template.html.md.erb