Add functionality by copy-pasting pre-generated certs to vm and update README.md

This commit includes the pre-generated certs in the files/certs
directory. README.md was thoroughly updated to include an example of
using certbot with this role and how to import the root.crt to Firefox.

templates/Caddyfile.j2

@@ -11,9 +11,6 @@
 localhost:8443 {
     acme_server {
         ca local
+        lifetime 720h
     }
-}
-
-# Refer to the Caddy docs for more information:
-# https://caddyserver.com/docs/caddyfile
-
+}