##### 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')
```
if create_new_password:
            prompt_formats['prompt'] = ['New vault password (%(vault_id)s): ',
                                        'Confirm new vault password (%(vault_id)s): ']
            
            prompt_formats['prompt_ask_vault_pass'] = ['New Vault password: ',
                                                       'Confirm New Vault password: ']
        else:
            prompt_formats['prompt'] = ['Vault password (%(vault_id)s): ']
            
            prompt_formats['prompt_ask_vault_pass'] = ['Vault password: ']
        vault_ids = CLI.build_vault_ids(vault_ids,
                                        vault_password_files,
                                        ask_vault_pass,
                                        create_new_password,
                                        auto_prompt=auto_prompt)
        for vault_id_slug in vault_ids:
            vault_id_name, vault_id_value = CLI.split_vault_id(vault_id_slug)
            if vault_id_value in ['prompt', 'prompt_ask_vault_pass']:
                
                
                built_vault_id = vault_id_name or C.DEFAULT_VAULT_IDENTITY
                
                
                
                
                prompted_vault_secret = PromptVaultSecret(prompt_formats=prompt_formats[vault_id_value],
                                                          vault_id=built_vault_id)
                
                
                try: