give cl65 alternative

doc/sim65.sgml

@@ -120,7 +120,7 @@ command line arguments to <tt/sim65/ will be passed to <tt/main/,
 and the return value from <tt/main/ will become sim65's exit code.
 The <tt/stdlib.h/ <tt/exit/ function may also be used to terminate with an exit code.
 
-Exit codes are limited to an unsigned 8 bit value.
+Exit codes are limited to an unsigned 8 bit value. (E.g. returning -1 will give an exit code of 255.)
 
 The standard C library high level file input and output is functional.
 A sim65 application can be written like a command line application,
@@ -141,8 +141,12 @@ int main()
 }
 
 // Build and run:
-//   cc65 -o example.s example.c
-//   ca65 -o example.o example.s
+//   cl65 -t sim6502 -o example.prg example.c
+//   sim65 example.prg
+
+// Build and run, separate steps:
+//   cc65 -t sim6502 -o example.s example.c
+//   ca65 -t sim6502 -o example.o example.s
 //   ld65 -t sim6502 -o example.prg example.o sim6502.lib
 //   sim65 example.prg
 </verb></tscreen>
@@ -173,7 +177,11 @@ _main:
     rts
 
 ; Build and run:
-;   ca65 -o example.o example.s
+;   cl65 -t sim6502 -o example.prg example.s
+;   sim65 example.prg
+
+; Build and run, separate steps:
+;   ca65 -t sim6502 -o example.o example.s
 ;   ld65 -t sim6502 -o example.prg example.o sim6502.lib
 ;   sim65 example.prg
 </verb></tscreen>