Add doc for deployment using tilt (#472)

Author: Amulyam24

docs/book/src/developer/tilt.md

@@ -1 +1,74 @@
 # Rapid iterative development with Tilt
+
+## Overview
+
+This document describes how to use [kind](https://kind.sigs.k8s.io) and [Tilt](https://tilt.dev) for a simplified workflow that offers easy deployments and rapid iterative builds.
+
+## Prerequisites
+
+1. [Docker](https://docs.docker.com/install/) v19.03 or newer
+2. [kind](https://kind.sigs.k8s.io) v0.9 or newer (other clusters can be
+   used if `preload_images_for_kind` is set to false)
+3. [kustomize](https://kubectl.docs.kubernetes.io/installation/kustomize/)
+4. [Tilt](https://docs.tilt.dev/install.html) v0.22.2 or newer
+5. [envsubst](https://github.com/drone/envsubst) or similar to handle
+   clusterctl var replacement
+6. Clone the [Cluster API](https://github.com/kubernetes-sigs/cluster-api) repository
+   locally
+7. Clone the [cluster-api-provider-ibmcloud](https://github.com/kubernetes-sigs/cluster-api-provider-ibmcloud) repository you want to deploy locally as well
+
+## Create a kind cluster
+
+First, make sure you have a kind cluster and that your `KUBECONFIG` is set up correctly:
+
+``` bash
+kind create cluster
+```
+
+This local cluster will be running all the cluster api controllers and become the management cluster which then can be used to spin up workload clusters on IBM Cloud.
+
+## Create a tilt-settings.json file
+
+Next, create a `tilt-settings.json` file and place it in your local copy of `cluster-api`. Here is an example:
+
+**Example `tilt-settings.json` for CAPI-IBM clusters:**
+
+Make sure to replace the parameter `IBMCLOUD_API_KEY` with a valid API key.
+
+```json
+{
+    "default_registry": "gcr.io/you-project-name-here",
+    "provider_repos": ["../cluster-api-provider-ibmcloud"],
+    "enable_providers": ["ibmcloud", "kubeadm-bootstrap", "kubeadm-control-plane"],
+    "kustomize_substitutions": {
+      "IBMCLOUD_API_KEY": "XXXXXXXXXXXXXXXXXX"
+    }
+}
+```
+**NOTE**: For information about all the fields that can be used in the `tilt-settings.json` file, check them [here](https://cluster-api.sigs.k8s.io/developer/tilt.html#tilt-settingsjson-fields).
+
+## Run Tilt
+
+To launch your development environment, run:
+
+``` bash
+tilt up
+```
+
+Kind cluster becomes a management cluster after this point, check the pods running on the kind cluster by running `kubectl get pods -A`.
+
+## Create workload clusters
+
+To provision your workload cluster, check the `Creating a cluster` section for [VPC](/topics/vpc/creating-a-cluster.html) and [PowerVS](/topics/powervs/creating-a-cluster.html). 
+
+After deploying it, check the tilt logs and wait for the clusters to be created.
+
+## Clean up
+
+Before deleting the kind cluster, make sure you delete all the workload clusters.
+
+```bash
+kubectl delete cluster <clustername>
+tilt up (ctrl-c)
+kind delete cluster
+```