Fix incorrect link to swift doc and swift package-registry login command (#29096) (#29103)

docs/content/usage/packages/overview.en-us.md

 | [PyPI](usage/packages/pypi.md) | Python | `pip`, `twine` |
 | [RPM](usage/packages/rpm.md) | - | `yum`, `dnf`, `zypper` |
 | [RubyGems](usage/packages/rubygems.md) | Ruby | `gem`, `Bundler` |
-| [Swift](usage/packages/rubygems.md) | Swift | `swift` |
+| [Swift](usage/packages/swift.md) | Swift | `swift` |
 | [Vagrant](usage/packages/vagrant.md) | - | `vagrant` |
 
 **The following paragraphs only apply if Packages are not globally disabled!**

docs/content/usage/packages/swift.en-us.md

 To register the package registry and provide credentials, execute:
 
 ```shell
-swift package-registry set https://gitea.example.com/api/packages/{owner}/swift -login {username} -password {password}
+swift package-registry set https://gitea.example.com/api/packages/{owner}/swift
+swift package-registry login https://gitea.example.com/api/packages/{owner}/swift --username {username} --password {password}
 ```
 
 | Placeholder  | Description |