##### SUMMARY
With the introduction of `Collection` mechanism using the `ansible-galaxy` CLI, the command and sub command help texts should be reflecting the new feature. The CLI currently validates the `collection` sub-command but the help text is still saying `role` is the only valid sub-command.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
`ansible-galaxy`

##### ANSIBLE VERSION
```
ansible 2.9.7
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/dvercill/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /home/dvercill/.local/lib/python3.8/site-packages/ansible
  executable location = /home/dvercill/.local/bin/ansible
  python version = 3.8.2 (default, Feb 28 2020, 00:00:00) [GCC 10.0.1 20200216 (Red Hat 10.0.1-0.8)]
```

##### CONFIGURATION
N/A

##### OS / ENVIRONMENT
Fedora Workstation 32 beta

##### STEPS TO REPRODUCE
```
$ ansible-galaxy doesnotexist
usage: ansible-galaxy role [-h] ROLE_ACTION ...
ansible-galaxy role: error: argument ROLE_ACTION: invalid choice: 'doesnotexist' (choose from 'init', 'remove', 'delete', 'list', 'search', 'import', 'setup', 'login', 'info', 'install')
```
''' prompt for connection and become passwords if needed '''
        op = context.CLIARGS
        sshpass = None
        becomepass = None
        become_prompt = ''
        become_prompt_method = "BECOME" if C.AGNOSTIC_BECOME_PROMPT else op['become_method'].upper()
        try:
            if op['ask_pass']:
                sshpass = getpass.getpass(prompt="SSH password: ")
                become_prompt = "%s password[defaults to SSH password]: " % become_prompt_method
            else:
                become_prompt = "%s password: " % become_prompt_method
            if op['become_ask_pass']:
                becomepass = getpass.getpass(prompt=become_prompt)
                if op['ask_pass'] and becomepass == '':
                    becomepass = sshpass
        except EOFError:
            pass
        
        
        if sshpass:
            sshpass = to_unsafe_text(sshpass)
        if becomepass:
            becomepass = to_unsafe_text(becomepass)
        return (sshpass, becomepass)
    def validate_conflicts(self, op, runas_opts=False, fork_opts=False):