chore: remove old entries from files field in `package.json

[G-Rath]

Was exploring the package locally and noticed these: I believe the completion scripts have been removed into completion-templates.ts, and am guessing that build use to be where the build output went?

It's good to remove them since makes the package.json a little smaller, but more importantly prevents publishing unneeded files.

fwiw LICENSE & index.js can actually be removed too as npm always included README, CHANGELOG, LICENCE and whatever main points at.

[mleguen]

Good shot for the hbs files, however we need the recently introduced build!

lib/**/*.js itself will disappear in a soon to come commit.

[mleguen]

Thanks!