Fix docs for CSV::Builder#row(&) (#14736)

Author: philipp-classen

src/csv/builder.cr

@@ -51,7 +51,7 @@ class CSV::Builder
     @first_cell_in_row = true
   end
 
-  # Yields a `CSV::Row` to append a row. A newline is appended
+  # Yields a `CSV::Builder::Row` to append a row. A newline is appended
   # to `IO` after the block exits.
   def row(&)
     yield Row.new(self, @separator, @quote_char, @quoting)