Update Package.swift

Correct the link.

Signed-off-by: LamTrinh.Dev <me@lamtrinh.dev>

Package.swift

@@ -23,6 +23,6 @@ let package = Package(
 #if swift(>=5.6)
   // Add the documentation compiler plugin if possible
   package.dependencies.append(
-    .package(url: "https://github.com/apple/swift-docc-plugin", from: "1.3.0")
+    .package(url: "https://github.com/swiftlang/swift-docc-plugin", from: "1.3.0")
   )
 #endif