where does l2tpd.conf live?

[cagney]

Describe the bug
The documentation says:

-c <config_file>
              Set an alternate config file.  Fallback configuration file is
              /etc/l2tpd/l2tpd.conf.

but strings suggests:

# strings `which xl2tpd` | grep etc
/etc/l2tpd/l2tp-secrets
/etc/l2tp/l2tpd.conf
/etc/xl2tpd/l2tp-secrets
/etc/xl2tpd/xl2tpd.conf

To Reproduce
Per documentation, put xl2tpd.conf in /etc/l2tpd/l2tpd.conf, ignored.
Ignore documentation and put xl2tpd.conf in /etc/xl2tpd/xl2tpd.conf and it works.

Expected behavior
A clear and concise description of where to put xl2tpd.conf

l2tp detail:

• xl2tpd[2587]: xl2tpd version xl2tpd-1.3.18 (Alpine)

xl2tpd.conf
Well if I knew where it was looking ...

[global]
listen-addr = 192.1.3.33
debug network = yes
force userspace = yes
ipsec saref = no

[lns default]
require chap = yes
refuse pap = yes
require authentication = yes
name = north.testing.libreswan.org
ppp debug = yes
pppoptfile = /etc/ppp/options.xl2tpd
length bit = yes

[lac server]
lns = 192.1.2.23