docs: add the README for the velero-plugin-mayastor

Signed-off-by: Abhinandan Purkait <[email protected]>

Author: Abhinandan-Purkait

README.md

@@ -0,0 +1,98 @@
+# Velero Mayastor Restore Plugin
+
+[![Build](https://github.com/openebs/velero-plugin/actions/workflows/build-release.yaml/badge.svg)](https://github.com/openebs/velero-plugin/actions/workflows/build-release.yaml)
+
+This Velero plugin for OpenEBS Mayastor ensures that `PersistentVolumeClaim` annotations related to StatefulSets (`openebs.io/stsAffinityGroup`) are updated correctly during Velero restores — especially when restoring into a different namespace.
+
+## ✨ Features
+
+- Updates the `openebs.io/stsAffinityGroup` annotation on PVCs during restore
+- Ensures StatefulSet PVC grouping works in multiple namespaces
+
+## 🧭 Project Structure
+
+```
+.
+├── main.go                           # Entry point that registers the plugin with Velero
+├── pkg/
+│   └── mayastor/
+│       └── plugin/
+│           └── restoreplugin.go      # Core restore plugin logic
+├── Dockerfile                        # Multi-stage Docker build for plugin image
+├── Makefile                          # Build, lint, container build, and utility targets
+├── _output/                          # Output binary and build artifacts
+├── go.mod / go.sum                   # Go module files
+└── README.md                         # This documentation
+```
+
+## 🛠️ Building
+
+### Prerequisites
+
+- [Docker](https://docs.docker.com/get-docker/)
+- [Make](https://www.gnu.org/software/make/)
+- [Go](https://go.dev/doc/install) 1.23+
+
+### Build Plugin Binary
+
+```sh
+make build
+```
+
+### Build Docker Image
+
+```sh
+make container
+```
+
+## 🧹 Linting & Formatting
+
+Run all linters and fail if formatting is required:
+
+```sh
+make lint
+```
+
+Auto-fix formatting issues:
+
+```sh
+make lint-fix
+```
+
+## 🧪 Usage with Velero
+
+1. Push the built image to your container registry:
+
+```sh
+docker tag openebs/velero-plugin-mayastor:<tag> <your-registry>/velero-plugin-mayastor:<tag>
+docker push <your-registry>/velero-plugin-mayastor:<tag>
+```
+
+2. Patch Velero deployment to use the plugin:
+
+```yaml
+spec:
+  template:
+    spec:
+      initContainers:
+      - image: docker.io/openebs/velero-plugin-mayastor:develop
+        imagePullPolicy: Always
+        name: velero-plugin-mayastor
+        resources: {}
+        terminationMessagePath: /dev/termination-log
+        terminationMessagePolicy: File
+        volumeMounts:
+        - mountPath: /target
+          name: plugins
+```
+
+## 🔍 How It Works
+
+- On restore, the plugin checks PVCs for the annotation `openebs.io/stsAffinityGroup`.
+- If it exists, it updates the namespace portion of the annotation value based on Velero’s restore namespace mapping.
+- If the namespace hasn't changed, the plugin logs and skips the update.
+- If the annotation `openebs.io/stsAffinityGroup` doesn't exist it skips the update.
+
+## 🤝 Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md) and [CODE_OF_CONDUCT.md](CODE_OF_CONDUCT.md)