epmd: pedantic spelling fix in comments

Correct spelling errors in the run_daemon() comments which describe
the redirection of stdin, stdout, and stderr to /dev/null for safety
reasons.

(Exceptionally pedantic but this was literally the first piece of code I decided to examine in the `otp` repository and it popped out at me. Present since at least the initial extended Erlang OTP history commit, b48c3645)