doc: Update README.md

Author: jaywcjlove

README.md

@@ -19,7 +19,7 @@ You can add MarkdownUI to an Xcode project by adding it as a package dependency.
 Or add the following to `Package.swift`:
 
 ```swift
-.package(url: "https://github.com/sindresorhus/is-camera-on", from: "1.0.0")
+.package(url: "https://github.com/jaywcjlove/markdown", from: "1.0.0")
 ```
 
 Or [add the package in Xcode](https://developer.apple.com/documentation/xcode/adding_package_dependencies_to_your_app).