You get that error because the perldoc script uses the 'more' command of the DOS command line shell (cmd.exe) to show you the perldoc. So cmd.exe has to be in the PATH too as well as any other program perldoc might need.

I don't know much about perl or shells on windows, but you might check if PATH (or path) already has a nice collection of paths before you overwrite it with 'path=...', so you might check that and just add the perl path to it instead of overwriting