oras: add page

[xinghewumeng]

Closes #22180

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR contains at most 5 new pages.
• The PR is authored by me, or has been human-reviewed if it was created with AI or machine translation software.
• The PR title conforms to the recommended templates.

---

Description

Add documentation page for oras, OCI Registry As Storage CLI.

Commands included

• Log in to a remote OCI registry (oras login)
• Push files to a registry with a specific tag (oras push)
• Pull files from a registry (oras pull)
• Copy an artifact between registries (oras copy)
• Tag an existing artifact in a registry (oras tag)
• List repositories in a registry (oras repo list)
• List tags for a repository in a registry (oras repo tags)
• Fetch and display the manifest of an artifact (oras manifest fetch)