additional checks suggestions

[hmenager]

non-expensive checks that could be added to codefair:

• check a code of conduct file is there
• check contributing guidelines are there

[fairdataihub-bot]

Hello! Thank you for opening this issue. Your input is valuable and helps improve the project. Can you please provide a detailed description of the problem you're encountering? Any additional information such as steps to reproduce the issue would be greatly appreciated. Thank you!

[hmenager]

code of conduct: https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/adding-a-code-of-conduct-to-your-project
contributing guidelines: https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors