Improve grammar of comments

closes https://github.com/official-stockfish/Stockfish/pull/4801

No functional change

src/movegen.h

@@ -56,8 +56,9 @@ inline bool operator<(const ExtMove& f, const ExtMove& s) {
 template<GenType>
 ExtMove* generate(const Position& pos, ExtMove* moveList);
 
-/// The MoveList struct is a simple wrapper around generate(). It sometimes comes
-/// in handy to use this class instead of the low level generate() function.
+/// The MoveList struct wraps the generate() function and returns a convenient
+/// list of moves. Using MoveList is sometimes preferable to directly calling
+/// the lower level generate() function.
 template<GenType T>
 struct MoveList {