Describe the bug

The listed options are routinely shown as having --optname [FLORP] where FLORP is now described as optional argument to the --optname.

This is a docs problem, since many of these require a value to work correctly.

To Reproduce
Steps to reproduce the behavior:

1. Go to lib/github_changelog_generator/parser.rb
2. Read the individual options defined
3. See issue that many are [OPTIONAL-VALUE] when they should not.

Expected behavior

--help output which matches what is true for option arity.

Additional context

This is a ✨ 📖 DOCUMENTATION ISSUE 📖 ✨ .