feat(nx-dev): allow custom media images

[isaacplmann]

Allows you to specify custom media images in map.json

Add a mediaImage property in the entry in map.json. The path is relative to /docs and no title or content text will be written over the top of the image.

Note the previews won't have the correct social media image because the social media image points to the live nx.dev site. You can verify your social media images by viewing [preview url]/images/open-graph/ci-features-remote-cache.jpg and replacing ci-features-remote-cache with the url for your page.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
nx-dev	✅ Ready (Inspect)	Visit Preview	Dec 5, 2023 7:12pm

[nx-cloud]

☁️ Nx Cloud Report

CI is running/has finished running commands for commit d0912b8. As they complete they will appear below. Click to see the status, the terminal output, and the build insights.

📂 See all runs for this CI Pipeline Execution

---

✅ Successfully ran 6 targets

• nx affected --target=e2e --base=43a4482482ce83e921aacb491b4a572bde2e52db --head=d0912b8b88a3abd585d186a3f50324b84143aadc --parallel=1
• nx affected --targets=lint,test,build --base=43a4482482ce83e921aacb491b4a572bde2e52db --head=d0912b8b88a3abd585d186a3f50324b84143aadc --parallel=3
• nx run-many -t check-imports check-commit check-lock-files check-codeowners documentation --parallel=1 --no-dte
• nx-cloud record -- nx format:check --base=43a4482482ce83e921aacb491b4a572bde2e52db --head=d0912b8b88a3abd585d186a3f50324b84143aadc
• nx documentation --no-dte
• nx affected -t e2e-macos --parallel=1 --base=43a4482482ce83e921aacb491b4a572bde2e52db --head=d0912b8b88a3abd585d186a3f50324b84143aadc

---

Sent with 💌 from NxCloud.

[juristr]

we should also update the docs/README to include this possibility so ppl know

[github-actions]

This pull request has already been merged/closed. If you experience issues related to these changes, please open a new issue referencing this pull request.