"Start Discussion" button navigates to 404 in markdown docs

[lukonik]

click on that button navigates to the 404 page

Link: https://tanstack.com/markdown/latest/docs/framework

[lukonik]

I checked the markdown repository (https://github.com/TanStack/markdown) and noticed it doesn't have a Discussions tab. Because of this, we should probably do one of the following:

• Conditionally hide the "Start Discussion" button.
• Enable the Discussions tab.

[tannerlinsley]

Source evidence: this page always renders a link to https://github.com/${library.repo}/discussions from src/routes/_library/$libraryId/$version.docs.framework.index.tsx, but GitHub reports that Discussions are disabled for TanStack/markdown. The link is therefore guaranteed to return 404 for Markdown, and there is no existing library capability flag for this distinction.

Two clean options:

1. Enable Discussions on TanStack/markdown, which keeps the current cross-library CTA and gives Markdown the same support path.
2. Add an explicit per-library capability and omit this CTA for repositories without Discussions. This avoids a dead link, but Markdown users would only see the Discord action on this page.

@tannerlinsley, the decision needed is whether Markdown should have a GitHub Discussions community surface. If yes, enable it in the repository settings. If no, the site should model that capability and hide this one action for Markdown.