docs: add contributing docs to site (aenix-io#112)

Move contribution guidelines to site

fixes aenix-io#105 aenix-io#103

site/content/en/docs/v0.1/contribution-guidelines/_index.md

@@ -4,4 +4,74 @@ weight: 10
 description: How to contribute to the project
 ---
 
-TODO
+etcd operator guide for developers.
+
+## How to start contributing
+First of all, etcd operator uses kubebuilder. [See official docs](https://book.kubebuilder.io/introduction) to learn
+more.
+
+### Easy way
+Using this way, you don't be able to debug the controller locally. After every change you will have to redeploy changes.
+#### Pre-requisites
+- [kind](https://kind.sigs.k8s.io/docs/user/quick-start/#installation)
+
+**Steps**
+1. Create and prepare kind cluster:
+    ```shell
+    make kind-prepare
+    ```
+
+2. Install CRDs into kind cluster
+    ```shell
+    make install
+    ```
+
+3. Build image and load it into kind cluster, deploy etcd-operator, RBAC, webhook certs
+    ```shell
+    make deploy
+    ```
+
+4. To deploy your code changes, redeploy etcd-operator:
+    ```shell
+    make redeploy
+    ```
+
+5. To clean up after all, delete kind cluster:
+    ```shell
+    make kind-delete
+    ```
+### Advanced way
+Using VSCode you can connect your IDE to a pod in kubernetes cluster and use `go run cmd/main.go` from the pod.
+It will allow you to debug easily and faster integrate code changes to you develop environment.
+
+**General steps**
+1. Install VSCode Kubernetes extension.
+2. Install VSCode Dev Containers extension.
+3. Create pvc to store operator code, go modules and your files.
+4. Build Dockerfile to create image for your develop environment (git, golang , etc...). Take base image that you love
+most.
+5. Patch operator deployment to
+   * Attach PVC from step 3.
+   * Change operator image to your image.
+   * Change command and args to endless sleep loop.
+   * Change rolling update strategy to recreate if you use RWO storage class.
+   * Change security context RunAsNonRoot to false.
+   * Increase requests and limits.
+   * Remove readiness and liveness probes.
+6. Attach VSCode to a running container through Kubernetes extension.
+7. Install necessary extensions to the container. They will be preserved after container restart if you attached pvc to
+home directory.
+8. Run `go run cmd/main.go`.
+
+
+## Release procedure
+Every PR should have a label to show what kind of changes does it bring. For example, PRs with docs changes should have
+`documentation` label. This labels will be used by the `release-drafter` workflow to prepare the release draft.
+
+### Cutting off a release
+When all tasks for the release are merged to `main` branch, maintainer should
+
+- create new minor or major version in `site` if it's not a patch release and merge this PR to `main` branch
+- check that tag has not been already created. If it has been, delete it
+- publish the release using draft, created by `release-drafter`
+- you are amazing :)