Computer Tips - How do I setup my letsencrypt certificate on Apache 2.4?

Date: 2017may5 OS: Linux Distro: RedHat/Fedora/CentOS Q. How do I setup my letsencrypt certificate on Apache 2.4? A.
SSLCertificateFile /etc/letsencrypt/live/$DOMAIN/cert.pem SSLCertificateKeyFile /etc/letsencrypt/live/$DOMAIN/privkey.pem SSLCertificateChainFile /etc/letsencrypt/live/$DOMAIN/chain.pem