Update contributor docs to talk about conventional commits

[terriko]

We've been trying out conventionalcommits.org -- it's going well, we should add it as a recommendation to the new contributor docs.

[P0intMaN]

Hello @terriko ,

Is anyone working on this? I would like to contribute to this issue. In fact, being a beginner myself, it would help me too as I would be able to learn more about conventionalcommits while creating the documentation.

Thanks!