Ran the install steps
git clone https://git.sr.ht/~ghost08/photon
cd photon
make
sudo make install
[sudo] password for ME:
Verification code:
scdoc < doc/photon.1.scd > photon.1
/bin/sh: 1: scdoc: not found
make: *** [Makefile:24: photon.1] Error 127
The was for Ubuntu 22.04 LTE
You need to install scdoc. It is in the default repositories. https://packages.ubuntu.com/jammy/scdoc
sudo apt install scdoc