Comments and improvements welcome.
in src/libinjection_sqli.c
edit the definition
#define LIBINJECTION_VERSION "3.9.1"
There isn't much of specific format. It's not GNU changelog style. Just make sure it looks good in markdown.
Something like this
make test
git commit -m 'VERSION'
This will get the version number from the file above and create a local and remote tag.
I would be great to dump a src tarball on github releases.