Is your feature request related to a problem? Please describe.

A man page should be added to the project for accessing the documentation using man(1):

$ man git-cliff

Describe the solution you'd like

Add a man page under docs/ in the root directory of the project. It should contain information about the command line arguments, configuration file sections/fields and the basic usage.

There are 2 possible ways that I can think of to achieve this:

• Add the markdown representation of a man page (for readability) and use a 3rd party tool for conversion.
  • docs/git-cliff.md
  • Tools for conversion: pandoc or mandown
  • README.md should be updated about conversion instructions.
• Add the groff file
  • docs/git-cliff.1
  • help2man(1) can be used for assistance.

Describe alternatives you've considered
None.

Additional context
None.