Document the need for dynamic = ["version"] in pyproject.toml, in README #77
Description
I understand it's implied and is used in the project itself (https://github.com/ofek/hatch-vcs/blob/48e8aba/pyproject.toml#L7C1-L7C22). But the README only shows an example of dynamic = ["urls"] which would mislead people unfamiliar w/ PEP 621.