Add example of size_t wrong usage

Signed-off-by: Stepanov Evgeniy <estepanov@arccn.ru>

examples/1_example_1.cpp

-#include <iostream>
-#include <cstddef>
-
-class vint {
-private:
-    int *data;
-public:
-    vint(std::size_t size) {std::cout<<size<<std::endl; data = new int[size];}
-    int get_value(std::size_t index) { return data[index]; }
-    void set_value(size_t index, int value) {data[index] = value;}
-};
-
-int main(void)
-{
-    vint a(-3);
-    for (uint i = 0; i < 3; ++i)
-        a.set_value(i, i);
-    for (uint i = 0; i < 3; ++i)
-        std::cout << a.get_value(i) << " ";
-    std::cout << std::endl;
-    return 0;
-}

examples/1_example_2.cpp

+#include <iostream>
+#include <cstddef>
+#include <string>
+
+int main(void)
+{
+    std::string example = "This is example string";
+    for (size_t i = example.size() - 1; i >= 0; i--) {
+        std::cout << example[i] << std::endl;
+    }
+    return 0;
+}