message: Add comment on custom channels not possible in combined grammars
diff: @@ -5,7 +5,8 @@ static const unsigned int CH_LINE_ESCAPE = 4;
  static const unsigned int CH_LINE_COMMENT = 5;
  }
  -//channels { LINE_ESCAPE, LINE_COMMENT}
  +//custom channels are not supported in combined grammars
  +//channels { CH_LINE_ESCAPE, CH_LINE_COMMENT}
  /* Process #define statements in a C file using fuzzy parsing.
  */
  @@ -248,12 +249,12 @@ COMMENT
  ;
  LINE_ESCAPE
  - //: '\\' '\r'? '\n' -> channel(LINE_ESCAPE)
  + //: '\\' '\r'? '\n' -> channel(CH_LINE_ESCAPE)
  : '\\' '\r'? '\n' -> channel(4)
  ;
  LINE_COMMENT
  - //: '//' ~[\r\n]* '\r'? -> channel(LINE_COMMENT)
  + //: '//' ~[\r\n]* '\r'? -> channel(CH_LINE_COMMENT)
  : '//' ~[\r\n]* '\r'? -> channel(5)
  ;
  