Add iostream and initialization

ch_1/initialization/main.cpp

@@ -0,0 +1,11 @@
+#include <iostream>
+
+int main() {
+    int x { 0 };
+    double pi { 3.1415 };
+    [[maybe_unused]] double tau { 6.2830 };
+
+    std::cout << pi;
+
+    return 0;
+}