fix error

ch09/README.md

@@ -1,4 +1,4 @@
-# Chapter 9. Sequential Containers
+# Chapter 9. Sequential Containers
 
 ## Exercise 9.1:
 >Which is the most appropriate—a vector, a deque, or a list—for the following program tasks?
@@ -94,6 +94,11 @@ const vector<int> v2;
 auto it1 = v1.begin(), it2 = v2.begin();
 auto it3 = v1.cbegin(), it4 = v2.cbegin();
 ```
+In gcc 4.8, will report error:
+error: inconsistent deduction for ‘auto’: ‘__gnu_cxx::__normal_iterator<int*, std::vector<int> >’ and then ‘__gnu_cxx::__normal_iterator<const int*, std::vector<int> >’ auto it1 = v1.begin(), it2 = v2.begin();
+the correct code should be
+auto it1 = v1.begin();
+auto  it2 = v2.begin(), it3 = v1.cbegin(), it4 = v2.cbegin();
 
 `it1` is `vector<int>::iterator`