Merge pull request #8197 from csukuangfj/csukuangfj-patch-1

Fix typos in the documentation for AutoBuffer. (#8197)

* Allocate 1000 floats to match the documentation

Fix the documentation of `AutoBuffer`. By default, the following code
```.cpp
cv::AutoBuffer<float> m;
```` 
allocates only 264 floats. But the comment in the demonstration code says it allocates 1000 floats, which is 
not correct.

* fix typo in the comment.

modules/core/include/opencv2/core/utility.hpp

@@ -102,7 +102,7 @@ CV_EXPORTS void setUseCollection(bool flag); // set implementation collection st
  \code
  void my_func(const cv::Mat& m)
  {
-    cv::AutoBuffer<float> buf; // create automatic buffer containing 1000 floats
+    cv::AutoBuffer<float> buf(1000); // create automatic buffer containing 1000 floats
 
     buf.allocate(m.rows); // if m.rows <= 1000, the pre-allocated buffer is used,
                           // otherwise the buffer of "m.rows" floats will be allocated
@@ -137,9 +137,9 @@ public:
     void resize(size_t _size);
     //! returns the current buffer size
     size_t size() const;
-    //! returns pointer to the real buffer, stack-allocated or head-allocated
+    //! returns pointer to the real buffer, stack-allocated or heap-allocated
     operator _Tp* ();
-    //! returns read-only pointer to the real buffer, stack-allocated or head-allocated
+    //! returns read-only pointer to the real buffer, stack-allocated or heap-allocated
     operator const _Tp* () const;
 
 protected:
@@ -147,7 +147,7 @@ protected:
     _Tp* ptr;
     //! size of the real buffer
     size_t sz;
-    //! pre-allocated buffer. At least 1 element to confirm C++ standard reqirements
+    //! pre-allocated buffer. At least 1 element to confirm C++ standard requirements
     _Tp buf[(fixed_size > 0) ? fixed_size : 1];
 };