check content pages (reactflow docs, xyflow blog, case studies)

[chrtze]

before publishing it, let's go through all the docs pages and make sure that:

• they have correct frontmatter / meta tags and
• there are no broken links
• there is no placeholder content (like @todo)
• there are no typos

we can split up the work, if needed @hayleigh-dot-dev.

[chrtze]

I created a new ticket for missing content: https://github.com/xyflow/web/issues/189

[chrtze]

The meta tags for the component are not being displayed correctly (tested in discord: https://discord.com/channels/771389069270712320/1003684763141427200/1168548699006324777). Maybe we can switch to something like BaseEdge component - React Flow