Delete Examples/package-info directory as outdated (swiftlang#7434)

This example package was created many years ago during an initial
attempt of versioning SwiftPM with semver. That approach has been
abandoned since then, and SwiftPM doesn't provide any stable API outside
of `PackageDescription` and `PackagePlugin` modules.

This example code can mislead users of SwiftPM to believe that it can be
consumed as a library with a stable API in other modules, which is
currently not the case.

Author: MaxDesiatov

Examples/package-info/Package.swift

@@ -664,12 +664,6 @@ let package = Package(
             name: "XCBuildSupportTests",
             dependencies: ["XCBuildSupport", "SPMTestSupport"],
             exclude: ["Inputs/Foo.pc"]
-        ),
-        // Examples (These are built to ensure they stay up to date with the API.)
-        .executableTarget(
-            name: "package-info",
-            dependencies: ["Workspace"],
-            path: "Examples/package-info/Sources/package-info"
         )
     ],
     swiftLanguageVersions: [.v5]