docs: add contribution guide

CONTRIBUTION.md

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+## Contribution
+
+This is great that you'd like to contribute to this project. All change requests should go through the steps described below.
+
+## Pull Requests
+
+**Please, make sure you open an issue before starting with a Pull Request, unless it's a typo or a really obvious error.** Pull requests are the best way to propose changes.
+
+## Conventional commits
+
+Our repository follow [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/#summary) specification.
+
+Pull requests should have a title that follows the specification, otherwise, merging is blocked. If you are not familiar with the specification simply ask maintainers to modify. You can also use this cheatsheet if you want:
+
+- `fix: ` prefix in the title indicates that PR is a bug fix and PATCH release must be triggered.
+- `feat: ` prefix in the title indicates that PR is a feature and MINOR release must be triggered.
+- `docs: ` prefix in the title indicates that PR is only related to the documentation and there is no need to trigger release.
+- `chore: ` prefix in the title indicates that PR is only related to cleanup in the project and there is no need to trigger release.
+- `test: ` prefix in the title indicates that PR is only related to tests and there is no need to trigger release.
+- `refactor: ` prefix in the title indicates that PR is only related to refactoring and there is no need to trigger release.
+
+What about MAJOR release? just add `!` to the prefix, like `fix!: ` or `refactor!: `
+What about MAJOR release? just add `!` to the prefix, like `fix!: ` or `refactor!: `
+
+## Resources
+
+- [How to Contribute to Open Source](https://opensource.guide/how-to-contribute/)
+- [Using Pull Requests](https://help.github.com/articles/about-pull-requests/)
+- [GitHub Help](https://help.github.com)