To get started, create a 0.1.0 tag for the "initial commit" GitHub created and then customise manifest.json to your liking. Everything will be done for you; just make sure you follow conventional commits.
As a rule of thumb, anything that doesn't drastically alter the mod or make sweeping changes that could break other mods should be either an enhancement (for improvements to existing parts of the mod), feat (for new parts of the mod) or fix (for bugfixes). You can specify the part of the mod you're changing like so: fix(epic feature): do this thing properly.
If you do drastically alter the mod or make sweeping changes that could break other mods, add an exclamation mark just before the :, and write BREAKING CHANGE: This thing is now this thing, which means this. in the "description" or "footer" of the commit.
An important note: the version for the mod starts at 0.1.0, which means the mod is in development. When you finalise the mod for its first release, add an exclamation mark before the : and the version will automatically be bumped to 1.0.0.