Update documentation.

- Supported Python 3 version (at time of writing 3.6 or later).

- [pre-commmit](https://pre-commit.com/) 2.0.0 or later.

- [Terraform](https://www.terraform.io/) (for the terraform hooks).

## Optional requirements

- [Terraform](https://www.terraform.io/) or [OpenTofu](https://opentofu.org/)

  (for the `terraform-*` hooks).

- [Packer](https://www.packer.io/) (for the `packer-*` hooks).

- [Docker Compose](https://docs.docker.com/compose/) (for the `docker-compose`

  hook).

## Example .pre-commit-config.yaml

### `terraform-fmt`

Format Terraform files using `terraform fmt`.

Requires an installed `terraform`.

Requires an installed `terraform`. If you wish to use `tofu` instead, set the

`TF_CLI` environment variable to `tofu`.

### `terraform-validate`

Validate Terraform modules using `terraform validate`.

Requires an installed `terraform`.

Requires an installed `terraform`. If you wish to use `tofu` instead, set the

`TF_CLI` environment variable to `tofu`.

### `packer-fix`