##### 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')
```
"""Process the command line args
        Subclasses need to implement this method.  This method validates and transforms the command
        line arguments.  It can be used to check whether conflicting values were given, whether filenames
        exist, etc.
        An implementation will look something like this::
            def post_process_args(self, options):
                options = super(MyCLI, self).post_process_args(options)
                if options.addition and options.subtraction:
                    raise AnsibleOptionsError('Only one of --addition and --subtraction can be specified')
                if isinstance(options.listofhosts, string_types):
                    options.listofhosts = string_types.split(',')
                return options
        """
        
        if hasattr(options, 'tags') and not options.tags:
            
            options.tags = ['all']
        if hasattr(options, 'tags') and options.tags:
            tags = set()
            for tag_set in options.tags:
                for tag in tag_set.split(u','):