Adding back the page on Governance

[proccaserra]

As per discussion during Berlin F2F meeting early June 2022.

as per @weiguUL:

• [ ] check https://rdmkit.elixir-europe.org/how_to_contribute
• [ ] check other projects.

key areas to cover:

• how to make contributions
• how to provide information to allow due credit for contributions (i.e. provide an ORCID)
• how to apply for editorial board position
• how to onboard new comers / new editors
• expected duties for each of the roles
• how to outboard / say goodbye to contributors stepping down from their roles