more defaults in `config.toml`

[T-256]

other options of init command also could be configurable:

      --no-readme                    Do not create a readme
      --build-system <BUILD_SYSTEM>  Which build system should be used? [default: hatchling] [possible values:
                                     hatchling, setuptools, filt, pdm]
      --license <LICENSE>            Which license should be used (SPDX identifier)?

[mitsuhiko]

I like the idea.