Update example to 1.0 (#111)

### Motivation

Example was still using the main branch.

### Modifications

Updated the dependency to 1.0.

### Result

Example can now be copied out by adopters getting started.

### Test Plan

N/A

Author: czechboy0

Examples/hello-world-cli-example/Package.swift

@@ -10,8 +10,7 @@ let package = Package(
     dependencies: [
         .package(
             url: "https://github.com/apple/swift-configuration",
-            // TODO: Update once 1.0.0 is tagged.
-            branch: "main",
+            from: "1.0.0",
             traits: [.defaults, "CommandLineArguments"]
         )
     ],