Added a README for dbgtool

extra/dbgtool/README.txt

@@ -0,0 +1,24 @@
+To use dbgtool.py you need to pass it the MS-DOS executable binary file,
+and optionally the output debug.exe script file name.
+
+Example:
+
+$ python ./dbgtool.py -i ./nc.exe -o nc.scr
+
+This will create a ASCII text file with CRLF line terminators called
+nc.scr.
+
+Such file can then be converted to its original portable executable with
+the Windows native debug.exe, that is installed by default in all Windows
+systems:
+
+> debug.exe < nc.scr
+
+To be able to execute it on Windows you have to rename it to end with
+'.com' or '.exe':
+
+> ren nc_exe nc.exe
+
+
+Happy hacking!
+Bernardo Damele A. G. <bernardo.damele@gmail.com>