Update chart with v0.6.0-rc1

Also update Kubernetes requirement to v1.12+

chart/Chart.yaml

@@ -1,8 +1,8 @@
 apiVersion: v1
 name: longhorn
-version: 0.5.0
-appVersion: v0.5.0
-kubeVersion: ">=v1.8.0-r0"
+version: 0.6.0-rc1
+appVersion: v0.6.0-rc1
+kubeVersion: ">=v1.12.0-r0"
 description: Longhorn is a distributed block storage system for Kubernetes powered by Rancher Labs.
 keywords:
 - longhorn

chart/values.yaml

@@ -4,11 +4,11 @@
 image:
   longhorn:
     engine: rancher/longhorn-engine
-    engineTag: v0.5.0
+    engineTag: v0.6.0-rc1
     manager: rancher/longhorn-manager
-    managerTag: v0.5.0
+    managerTag: v0.6.0-rc1
     ui: rancher/longhorn-ui
-    uiTag: v0.5.0
+    uiTag: v0.6.0-rc1
   pullPolicy: IfNotPresent
 
 service: