Fix a type of playbook_command and add description more on doc

[maruloop]

When ansible was installed into rye or pipenv, I needed to specify playbook_command like the below.

OK:

ansible.playbook_command = ["rye", "run", "ansible-playbook"]

When I specified it as a String type, Vagrant raised an exception.

NG:

ansible.playbook_command = "rye run ansible-playbook"

[hashicorp-cla]

All committers have signed the CLA.

[chrisroberts]

@maruLoop Do you have the exception information available that Vagrant generated?

[maruloop]

@chrisroberts

In the Vagrantfile,

  config.vm.provision "ansible" do |ansible|
    ansible.playbook = "myplaybook.yml"
    ansible.playbook_command = "rye run ansible-playbook"
  end

I got this error.

The Ansible software could not be found! Please verify
that Ansible is correctly installed on your host system.

If you haven't installed Ansible yet, please install Ansible
on your host system. Vagrant can't do this for you in a safe and
automated way.
Please check https://docs.ansible.com for more information.