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##### SUMMARY
The "source" folder of my collection contains several files that are not directly related to the collection itself. E.g. a `.gitignore`, a `.github` folder, a `Makefile` etc.
When using `ansible-galaxy collection build <folder>`, these files are included in the generated tarball. This is especially hurtful when the source folder also contains a Python venv that I use for developing.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
ansible-galaxy

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.0.dev0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/egolov/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /home/egolov/Devel/ansible/ansible/lib/ansible
  executable location = /home/egolov/Devel/ansible/ansible/bin/ansible
  python version = 2.7.15 (default, Oct 15 2018, 15:26:09) [GCC 8.2.1 20180801 (Red Hat 8.2.1-2)]

```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
empty
```

##### OS / ENVIRONMENT
Fedora


##### STEPS TO REPRODUCE
Build a collection :)

##### EXPECTED RESULTS
I'd expect only collection-relevant files/folders (those that are listed in the spec/docs) to be included.


##### ADDITIONAL INFORMATION
Alternatively, a ignore file as suggested by @bcoca  in https://github.com/ansible/ansible/pull/59121/files#r304554334 could be a fix for this.

return os.path.abspath(os.path.expanduser(os.path.expandvars(path)))
    @staticmethod
    def _get_skeleton_galaxy_yml(template_path, inject_data):
        with open(to_bytes(template_path, errors='surrogate_or_strict'), 'rb') as template_obj:
            meta_template = to_text(template_obj.read(), errors='surrogate_or_strict')
        galaxy_meta = get_collections_galaxy_meta_info()
        required_config = []
        optional_config = []
        for meta_entry in galaxy_meta:
            config_list = required_config if meta_entry.get('required', False) else optional_config
            value = inject_data.get(meta_entry['key'], None)
            if not value:
                meta_type = meta_entry.get('type', 'str')
                if meta_type == 'str':
                    value = ''
                elif meta_type == 'list':
                    value = []
                elif meta_type == 'dict':
                    value = {}
            meta_entry['value'] = value
            config_list.append(meta_entry)
        link_pattern = re.compile(r"L\(([^)]+),\s+([^)]+)\)")
        const_pattern = re.compile(r"C\(([^)]+)\)")
        def comment_ify(v):