Install certbot on an AL2 Lightsail instance
I ended up not using certbot
for managing my LetsEncrypt SSL certificates, but I did learn how to install it:
# Need to first enable & install "EPEL" repo which will
# have `certbot` for AL2.
sudo amazon-linux-extras enable epel=stable
sudo yum install epel-release
# Then install certbot.
sudo yum install certbot