message: [doc] Change return type of is_word_boundary to bool
  is_word_boundary example using C++ iterators was incorrectly returning
  void, while it should return bool.
diff: @@ -1362,7 +1362,7 @@ Appendix 3: D Ranges and Algorithmic Complexity
  As currently defined, D's ranges make it difficult to implement algorithms over bidirectional sequences that take a position in the middle as an argument. A good example is a hypothetical `is_word_boundary` algorithm. In C++ with iterators, it might look like this:
  template< BidirectionalIterator I >
  - void is_word_boundary( I begin, I middle, I end )
  + bool is_word_boundary( I begin, I middle, I end )
  {
  bool is_word_prev = middle == begin ? false : isword(*prev(middle));
  bool is_word_this = middle == end ? false : isword(*middle);
  