docs(cli): document argument parsing

README.md

@@ -6,6 +6,7 @@ one consistent API on Windows and Linux.
 ## Features
 
 - Native open, save, folder, message, input, and color dialogs
+- Command-line flags, values, integers, and positional arguments
 - UTF-8 text clipboard access
 - Standard application, user, temporary, and executable paths
 - Non-blocking process launch
@@ -44,6 +45,13 @@ Include individual feature headers or the complete API:
 ```cpp
 #include <izo/iZo.hpp>
 
+izo::CommandLine args(argc, argv);
+if (args.Has("--verbose")) {
+    // Enable verbose logging.
+}
+const auto configPath = args.Get("--config");
+const int threads = args.GetInt("--threads", 4);
+
 izo::DialogOptions options;
 options.title = "Choose an image";
 options.filters = {{"Images", {"*.png", "*.jpg"}}};