Pretty trivial, but the file /usr/doc/sendmail-8.11.0/README.cf is mentioned twice in the comments in /etc/mail/sendmail.mc. With the new filesystem layout that RedHat 7.0 adheres to and the fact that the sendmail documentation is a separate package, the correct path to the file is /usr/share/doc/sendmail/README.cf
I have fixed that in /etc/mail/access.