Document module dependencies

[ssbarnea]

This adds a list of currently used dependencies in our documentation, with few words regarding how we plan to deal with them.

$ pipdeptree -p ansible-lint
ansible-lint==4.3.0a5.dev12+gb435e69
  - ansible [required: >=2.8, installed: 2.9.11]
    - cryptography [required: Any, installed: 3.0]
      - cffi [required: >=1.8,!=1.11.3, installed: 1.14.0]
        - pycparser [required: Any, installed: 2.20]
      - six [required: >=1.4.1, installed: 1.15.0]
    - jinja2 [required: Any, installed: 2.11.2]
      - MarkupSafe [required: >=0.23, installed: 1.1.1]
    - PyYAML [required: Any, installed: 5.3.1]
  - pyyaml [required: Any, installed: 5.3.1]
  - ruamel.yaml [required: >=0.15.37,<1, installed: 0.16.10]
    - ruamel.yaml.clib [required: >=0.1.2, installed: 0.2.0]

[webknjaz]

https://ansible-lint--817.org.readthedocs.build/en/817/CONTRIBUTING.html looks good