docs: proposal process (#89)

Author: vknabel

docs/contributing/01-Proposals/index.md

@@ -8,7 +8,7 @@ sidebar_position: 1
 
 This section contains proposals which address substantial modifications to metal-stack.
 
-Every proposal has a short name which starts with _MEP_ followed by an incremental, unique number. Proposals should be raised as pull requests in the [docs](https://github.com/metal-stack/docs) repository and can be discussed in Github issues.
+Every proposal has a short name which starts with _MEP_ followed by an incremental, unique number. Proposals should be raised as pull requests in the [website](https://github.com/metal-stack/website) repository and can be discussed in Github issues.
 
 The list of proposals and their current state is listed in the table below.
 
@@ -43,3 +43,27 @@ Once a proposal was accepted, an issue should be raised and the implementation s
 | [MEP-16](MEP16/README.md) | Firewall Support for Cluster API Provider      | `In Discussion` |
 | [MEP-17](MEP17/README.md) | Global Network View                            | `In Discussion` |
 | [MEP-18](MEP18/README.md) | Autonomous Control Plane                       | `In Discussion` |
+
+## Proposal Process
+
+1. Before starting a new proposal, it is advised to have a quick chat with one of the maintainers.
+2. Create a draft pull request in the [website](https://github.com/metal-stack/website) repository with your proposal. Your proposal doesn't have to be finished at this point.
+3. Share the PR in the [metal-stack Slack](https://metal-stack.slack.com/) and invite maintainers to review it.
+4. The review itself will probably take place in multiple iterations. Don't be discouraged if your proposal is not accepted right away. The goal is to reach consensus.
+5. Once your proposal is accepted, create an umbrella issue in the relevant repository or when multiple repositories are involved in the [releases](https://github.com/metal-stack/releases).
+6. Other issues should be created in different repositories and linked to the umbrella issue.
+7. Unless stated otherwise, the proposer is responsible for the implementation of the proposal.
+
+## How to Write a Good MEP
+
+In the first section of your MEP, start with the current situation and the motivation for the change. Summarize your proposal briefly.
+
+Next follows the main part: describe your proposal in detail. Which parts of of metal-stack are affected? Are there API changes? If yes, describe them and provide examples here.
+Try to think of side effects your proposal might have. Try to provide a view on how your proposal affects users of metal-stack.
+Highlight breaking changes and think of a migration path for existing users. If your proposal affects multiple components, try to describe the interaction between them.
+
+After the main part of your proposal, feel free to add additional sections, e.g. about alternatives that were considered, non-goals or future possibilities.
+
+Depending on the complexity of your proposal, you might want to add a section about the implementation plan or roadmap.
+
+You can have a look at the existing MEPs for inspiration. As you will notice: not every MEP has the same structure. Feel free to structure your MEP in a way that makes sense for your proposal.