[Docs] Broken link to Swift page in implementations.rst

[chilin0525]

Describe the bug, including details regarding any error messages, version, and platform.

The Swift documentation link in [docs/source/implementations.rst](

arrow/docs/source/implementations.rst

Line 124 in 235841d

Swift <https://github.com/apache/arrow-swift/blob/main/Arrow/README.md>

) returns a 404 error.

Current broken link: https://github.com/apache/arrow-swift/blob/main/Arrow/README.md

Component(s)

Documentation

[kou]

Issue resolved by pull request 49101
#49101