Documentation: Update the contributing guide

[rluders]

Is your feature request related to a problem? Please describe. Since we are going to adopt semver we need to update our contributing guide.

Describe the solution you'd like

My suggestions for some topics:

• How to contribute?
  • How to commit? (commitizen friendly)
  • Review process
• How the release process works?
  • What is semver?
  • CI/CD

Describe alternatives you've considered n/a

Additional context n/a