Merge pull request #682 from smzztx/patch-3

Update README.md

ch09/README.md

@@ -114,7 +114,7 @@ auto it2 = v2.begin(), it3 = v1.cbegin(), it4 = v2.cbegin();
 >Show an example of each of the six ways to create and initialize a vector. Explain what values each vector contains.
 
 ```cpp
-vector<int> vec;    // 0
+vector<int> vec;    // vec is empty
 vector<int> vec(10);    // 0
 vector<int> vec(10, 1);  // 1
 vector<int> vec{ 1, 2, 3, 4, 5 }; // 1, 2, 3, 4, 5