fix perldoc in Acme::MilkyHolmes::Character

an error occurred with following message.
*Can't locate Acme/MilkyHolmes/SherlockShellingford.pm in @INC (you may need to install the Acme::MilkyHolmes::SherlockShellingford module)* ... 

fixed `Acme::MilkyHolmes::SherlockShellingford` namespace to `Acme::MilkyHolmes::Character::SherlockShellingford`