pipenv install documentation
Also mention that
`if no packages are given` sounds a bit better than `if none is given` when referring to `provided packages`. Also mention that `pipenv install` with no provided packages installs all packages from Pipfile. It is not obvious for people new to pipenv whether pipenv is using Pipfile or Pipfile.lock by default.
By default, `pipenv install` will install packages based on the list in `Pipfile`, not `Pipfile.lock`. `pipenv install --dev` is no exception. I've tested this using pipenv 2018.7.1 with different package versions in `Pipfile` and `Pipfile.lock`. After `pipenv install`, the versions in `Pipfile` were the ones actually installed.