Update ports properties and README

[bamurtaugh]

Based on discussion in microsoft/vscode-remote-release#4838, updating the ports properties in devcontainer.json and the README.

• Add otherPortsAttributes to devcontainer.json and a comment description above it, but leave it commented out
• Group all the ports properties together sequentially in the devcontainer.json: forwardPorts, portsAttributes, otherPortsAttributes
• Update portsAttributes:
  • Replace "3000" with regex
  • Remove "notify" behavior on autoforward since it led to two ports being shown, which could be confusing to users
  • Update in-line comment describing the property
• Update README:
  • In the section about container rebuild to see changes take effect, it used to describe uncommenting forwardPorts. But with portsAttributes and dynamic port forwarding, it feels like making changes to attributes in this property might be the most interesting to users, so I've updated the section to describe how to open a browser on autoforward.

Please let me know any thoughts you have on the above changes - happy to discuss further, make some modifications, or describe things more clearly for users via comments or the README.

Once we decide on a format that works well for the devcontainer.json and README here, I'll extend the same to the other remote samples and merge in changes there.

[Chuxel]

LGTM!

[alexr00]

👍

[wattsjohnny2020]

I