Add how to install operator locally; fix telegram link

HOW-TO-START-DEVELOPMENT.md

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+# How to start contributing
+
+## Read kubebuilder documentation
+[Docs](https://book.kubebuilder.io/introduction)
+
+## Build your develop environment
+
+### Easy way
+1. Download and install [kind](https://kind.sigs.k8s.io/docs/user/quick-start/#creating-a-cluster).
+2. Create lind cluster `kind create cluster --name etcd-operator-kind`.
+3. Switch kubectl context to kind `kubectl cluster-info --context kind-etcd-operator-kind`. Be attentive to avoid damaging your production environment.
+4. Install cert-manager (it creates certificate k8s secrets). Refer to the [docs](https://cert-manager.io/docs/installation/helm/#4-install-cert-manager).
+5. Build docker image *controller:latest* `make docker-build`.
+6. Retag image to upload to kind cluster with correct name `docker tag controller:latest ghcr.io/aenix-io/etcd-operator:latest`.
+7. Load image to kind cluster `kind load docker-image ghcr.io/aenix-io/etcd-operator:latest`.
+8. Install CRDs `make install`.
+9. Deploy operator, RBAC, webhook certs `make deploy`.
+
+To deploy your code changes
+1. Rebuild the image `make docker-build`.
+2. Retag image to upload to kind cluster with correct name `docker tag controller:latest ghcr.io/aenix-io/etcd-operator:latest`.
+3. Load image to kind cluster `kind load docker-image ghcr.io/aenix-io/etcd-operator:latest`.
+4. Redeploy yaml manifests if necessary `make deploy`.
+5. Restart etcd-operator `kubectl rollout restart -n etcd-operator-system deploy/etcd-operator-controller-manager`.
+
+### Advanced way
+Using *easy way* you will not be able to debug golang code locally and every change will be necessary to build as an image, upload to the cluster and then restart operator.
+If you use 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`.

README.md

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 [![Open Source](https://img.shields.io/badge/Open-Source-brightgreen)](https://opensource.org/)
 [![Apache-2.0 License](https://img.shields.io/github/license/aenix-io/etcd-operator)](https://opensource.org/licenses/)
-[![Telegram](https://img.shields.io/badge/Telegram-2CA5E0?style=flat&logo=telegram&logoColor=white)](https://t.me/etcd-operator)
+[![Telegram](https://img.shields.io/badge/Telegram-2CA5E0?style=flat&logo=telegram&logoColor=white)](https://t.me/etcd_operator)
 [![Active](http://img.shields.io/badge/Status-Active-green.svg)](https://aenix.io/etcd-operator/)
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 [![GitHub Commit](https://img.shields.io/github/commit-activity/y/aenix-io/etcd-operator)](https://github.com/aenix-io/etcd-operator)