Add two troubleshooters

[danmoseley]

Going through the CSS troubleshooters, it will take time to migrate them into the docs. Starting with the two easiest.

---

Internal previews

📄 File	🔗 Preview link
docs/troubleshooting/connection-string-missing.md	Connection string is missing
docs/troubleshooting/container-runtime-unhealthy.md	Container runtime appears to be unhealthy

[IEvangelist]

We need these to show up in the TOC, look for the toc.yml file, and add these next to the existing toubleshooting bits.

[danmoseley]

We need these to show up in the TOC, look for the toc.yml file, and add these next to the existing toubleshooting bits.

Looks like index.yml in a very similar way

[danmoseley]

addressed

[IEvangelist]

We need these to show up in the TOC, look for the toc.yml file, and add these next to the existing toubleshooting bits.

Looks like index.yml in a very similar way

Yes, they're similar. The index.ymlnis for the hub page with the links on the card UX.