clarify not found error message a bit.
tree582b5fa89bc63da6db78f48b5598f5d267cef886
-rwxr-xr-x 2422 LICENSE
-rwxr-xr-x 2014 Makefile
drwxr-xr-x - boot
drwxr-xr-x - commands
drwxr-xr-x - docs
drwxr-xr-x - drivers
drwxr-xr-x - etc
drwxr-xr-x - include
drwxr-xr-x - kernel
drwxr-xr-x - lib
drwxr-xr-x - man
drwxr-xr-x - servers
drwxr-xr-x - test
drwxr-xr-x - tools