The template is in the template.html file. Note that comment markers are
used to control how the template.awk Awk script generates the C header
which gets ultimately included in the compiled object code. Comment markers
have the <!-- var identifier --> format. Here identifier must be
a valid C identifier. All the text following the marker until the next
marker will be flattened into a C string.
If the identifier is NONE (capitalized) the text from that marker up to
the next marker will be discarded.
You will need Awk. I hope any decent implementation will do, but the GNU one is known to work flawlessly. Just do:
$ awk -f template.awk template.html > template.h
If your copy of awk is not the GNU implementation, you will need to
install it and use gawk instead in the command line above.
This includes macOS where the current built-in awk (currently version
20070501 at time of testing on 10.13.6) doesn't apply correctly and causes
characters to be omitted from the output. gawk can be installed with a
package manager such as Homebrew.