add about the forking workflow for Pull request

Does the forking workflow need to be more clear?

in the contributing file ([link](https://github.com/epiverse-trace/tutorials/blob/main/CONTRIBUTING.md)), there is already a mention to the forking workflow ([link](https://github.com/epiverse-trace/tutorials/blob/969a11b992972113a1610b7d36421c1c1a23caeb/CONTRIBUTING.md?plain=1#L158)), but is not as explicit as in the packages for a PR process ([link](https://github.com/epiverse-trace/.github/blob/main/CONTRIBUTING.md))

this is to request to make this explicit on top of the file. or to make a derivative from the project contributing file.