Thanks, but I did include it exactly because of this already!
[6] Add the following contents, preferably in the right section (somewhere where there's
HiddenServiceDir stuff commented out).
HiddenServiceDir /var/lib/tor/electrs_hidden_service/
HiddenServiceVersion 3
HiddenServicePort 50001 127.0.0.1:50001
ExitPolicy reject *:* # no exits allowed