<!--- Verify first that your improvement is not already reported on GitHub -->
<!--- Also test if the latest release and devel branch are affected too -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Explain the problem briefly below, add suggestions to wording or structure -->

https://docs.ansible.com/ansible/latest/collections/ansible/builtin/password_lookup.html :

> Define comma separated list of names that compose a custom character set in the generated passwords.
> They can be either parts of Python's string module attributes (ascii_letters,digits, etc) or are used literally ( :, -).

I suggest to list all possible names or at least add a link to python string module documentation: https://docs.python.org/3/library/string.html

Now you have to search for the relevant python documentation yourself.

<!--- HINT: Did you know the documentation has an "Edit on GitHub" link on every page ? -->

##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
<!--- Write the short name of the rst file, module, plugin, task or feature below, use your best guess if unsure -->
ansible.builtin.password

##### ADDITIONAL INFORMATION
<!--- Describe how this improves the documentation, e.g. before/after situation or screenshots -->

<!--- HINT: You can paste gist.github.com links for larger files -->

'''Generate a string containing all valid chars as defined by ``characters``
    :arg characters: A list of character specs. The character specs are
        shorthand names for sets of characters like 'digits', 'ascii_letters',
        or 'punctuation' or a string to be included verbatim.
    The values of each char spec can be:
    * a name of an attribute in the 'strings' module ('digits' for example).
      The value of the attribute will be added to the candidate chars.
    * a string of characters. If the string isn't an attribute in 'string'
      module, the string will be directly added to the candidate chars.
    For example::
        characters=['digits', '?|']``
    will match ``string.digits`` and add all ascii digits.  ``'?|'`` will add
    the question mark and pipe characters directly. Return will be the string::
        u'0123456789?|'
    '''
    chars = []
    for chars_spec in characters:
        
        
        chars.append(to_text(getattr(string, to_native(chars_spec), chars_spec),
                     errors='strict'))
    chars = u''.join(chars).replace(u'"', u'').replace(u"'", u'')
    return chars
def _parse_content(content):