Fix Dockerfile preview image URLs

Looks like a localhost development URL snuck in.

Author: rosszurowski

Dockerfile

@@ -25,7 +25,7 @@ LABEL org.opencontainers.image.title="Tailscale" \
     org.opencontainers.image.vendor="Tailscale Inc." \
     com.docker.desktop.extension.icon="https://tailscale.com/files/tailscale-docker-icon.svg" \
     com.docker.desktop.extension.api.version=">=0.2.3" \
-    com.docker.extension.screenshots='[{"alt": "A list of Docker containers in the Tailscale extension. A caption that says: Connect Docker to your private network. Share development servers with teammates, or remotely access private resources.", "url": "https://tailscale.com/files/images/docker/docker-screenshot-1.png"},{"alt": "A Docker container with a tooltip that says Open in Browser. A browser next to it with a website. A caption that says Easy access, from anywhere. Tailscale gives your containers a static IP and easy DNS name. It works even across firewalls and containerization layers.", "url": "http://localhost:9000/files/images/docker/docker-screenshot-1.png"}]' \
+    com.docker.extension.screenshots='[{"alt": "A list of Docker containers in the Tailscale extension. A caption that says: Connect Docker to your private network. Share development servers with teammates, or remotely access private resources.", "url": "https://tailscale.com/files/images/docker/docker-screenshot-1.png"},{"alt": "A Docker container with a tooltip that says Open in Browser. A browser next to it with a website. A caption that says Easy access, from anywhere. Tailscale gives your containers a static IP and easy DNS name. It works even across firewalls and containerization layers.", "url": "https://tailscale.com/files/images/docker/docker-screenshot-2.png"}]' \
     com.docker.extension.detailed-description="<p>Tailscale’s Docker Desktop extension lets you connect your containers to your Tailscale network. Any containers with exposed ports are available to others on the same tailnet (Tailscale network).</p><p>Tailscale lets you:</p><ul><li>Share development servers with your teammates</li><li>Access databases and sensitive development resources without exposing them to the public internet</li><li>Use <em>MagicDNS</em> to obtain shortnames for accessing your devices and containers</li></ul><h3>About Tailscale</h3><p>Tailscale lets you create a secure, virtual private network to connect your devices in minutes. This network connects devices anywhere in the world, no matter what firewalls or containerization layers are in-between them. And Tailscale provides robust access control rules enforced by each device, so users on your network can only access what they’re allowed to.</p><p>For more details, visit <em>tailscale.com</em>." \
     com.docker.extension.publisher-url="https://tailscale.com"\
     com.docker.extension.additional-urls='[{"title":"Website","url":"https://tailscale.com/"},{"title":"Documentation","url":"https://tailscale.com/kb/"},{"title":"Support","url":"https://tailscale.com/contact/support"},{"title":"Terms of Service","url":"https://tailscale.com/terms"},{"title":"Privacy policy","url":"https://tailscale.com/privacy-policy"}]'