Getting the ACCOUNT_THUMBPRINT into haproxy.cfg

[tuck1s]

I started from this tutorial which explains the advantages of using acme.sh for haproxy, i.e.

• works well with TLS SNI, can have many different certs in a directory
• Puts the cert/key combined.pem file in the right place
• Does a "hot update" of haproxy with no need to restart the service (important for service continuity)

One slightly tricky thing is: how to get the ACCOUNT_THUMBPRINT out afterward, i.e. beyond the point when initial account registration is done? (It's in backscroll and not easy to automate).
It would be nice to automate that, possibly using sed -i to update my haproxy.cfg.