Restarted the production of the app

libs/CLI11/book/code/simplest.cpp

@@ -0,0 +1,11 @@
+#include "CLI/CLI.hpp"
+
+int main(int argc, char **argv) {
+    CLI::App app;
+
+    // Add new options/flags here
+
+    CLI11_PARSE(app, argc, argv);
+
+    return 0;
+}