Update dev container content

[bamurtaugh]

Based on team discussions and customer feedback, we've been assembling a list of docs to update: #5737.

Summary of changes:

• Revisit Advanced Containers, removing one topic and adding a new one (help reduce the length of containers.md by extracting the git credential section into a new advanced page)
• Update based on latest spec and CLI updates, terminology, and guidance
  • Major one was updating devcontainer.json examples to follow the latest spec and point to the latest images
• Changes based on customer feedback, including content that was outdated or wording/info that was confusing
• Separately, I updated aka.ms links along with CLI output info in containers.dev and devcontainers/cli
• As the last remaining item in issue 5737, I'll also separately update our dev container Learn module after this

[samruddhikhandale]

Looks great, left minor comments!

[bamurtaugh]

Thanks so much for the fast review, @samruddhikhandale! Merged all your suggestions.

[samruddhikhandale]

Thanks! Missed -bullseye in two other places.

[bamurtaugh]

Thanks! Just merged those changes in.

[Chuxel]

In the CLI section, we still tell people to add their features again to the secondary devcontainer.json. That's no longer required in the image pre-build situation so...

1. Create a simplified devcontainer.json file in repositories where you'd like to use the image - the devcontainer.json should either use the image property or reference the image in an associated Docker Compose file. For example:

   {
       "image": "ghcr.io/your-org/your-image-name"
   }

[bamurtaugh]

@Chuxel thanks so much for the detailed review! I believe I've addressed and replied to your comments above.

[Chuxel]

One thing I'm not sure we have a good link to anywhere is image metadata. We allude to it in the pre-builds section but we're a bit more specific in the containers.dev docs.

https://containers.dev/implementors/reference/#labels

EDIT: In fact, I noticed a couple bad links, and refreshed the Dev Container spec section on this as well: devcontainers/devcontainers.github.io#122

[bamurtaugh]

Thanks @Chuxel! I expanded the info on metadata in the pre-build section (like what you added in the linked containers.dev PR), and I added links to this content from the Notes I had added on metadata throughout other docs.

[bamurtaugh]

@gregvanl This is ready for your review and merge whenever you're ready!

[chrmarti]

LGTM, 2 nits.