[iterators][segment_iterator] fix grammar in the comment about the

iterator category of the segment iterator

include/boost/geometry/iterators/segment_iterator.hpp

@@ -278,7 +278,7 @@ public:
     // fact that the value type of the iterator is not a reference,
     // the iterator_facade framework (used to define the base class of
     // this iterator) degrades automatically the iterator's category
-    // to input iterator. With following typedef we recover the
+    // to input iterator. With the following typedef we recover the
     // correct iterator category.
     typedef std::bidirectional_iterator_tag iterator_category;