Fixed some missing "verilog_" in documentation

frontends/verilog/preproc.cc

@@ -28,7 +28,7 @@
  *
  *  Ad-hoc implementation of a Verilog preprocessor. The directives `define,
  *  `include, `ifdef, `ifndef, `else and `endif are handled here. All other
- *  directives are handled by the lexer (see lexer.l).
+ *  directives are handled by the lexer (see verilog_lexer.l).
  *
  */
 

frontends/verilog/verilog_lexer.l

@@ -28,7 +28,7 @@
  *
  *  A simple lexer for Verilog code. Non-preprocessor compiler directives are
  *  handled here. The preprocessor stuff is handled in preproc.cc. Everything
- *  else is left to the bison parser (see parser.y).
+ *  else is left to the bison parser (see verilog_parser.y).
  *
  */