README update for ConfigMap reload sample (#401)

* Updated README with the following:
1. Fixed small typos
2. Removed notes about Spring Boot liveness and readiness check related
to Fabric8 since that issue has been resolved and is working as expected
3. Added sample configuration files for K8s RBAC set up required for the
example to work
4. Added section about how to setup RBAC config

* Updated sample RBAC configuration with a less privileged role example

spring-cloud-kubernetes-examples/kubernetes-reload-example/src/k8s/rb.yml

@@ -0,0 +1,13 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: pod-reader
+  namespace: default
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: pod-reader
+subjects:
+  - kind: ServiceAccount
+    name: config-reader
+    namespace: default

spring-cloud-kubernetes-examples/kubernetes-reload-example/src/k8s/role.yml

@@ -0,0 +1,9 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  namespace: default
+  name: pod-reader
+rules:
+  - apiGroups: [""]
+    resources: ["pods","configmaps"]
+    verbs: ["get", "watch", "list"]

spring-cloud-kubernetes-examples/kubernetes-reload-example/src/k8s/sa.yml

@@ -0,0 +1,5 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: config-reader
+  namespace: default