added region check step, route53 config.

doc/howto/usage/k8s/k8s_aws_en.md

 # Kubernetes on AWS
+## Choose AWS Service Region
+This tutorial requires several AWS services work in the same region. Before we create anything in AWS, please check the following link
+https://aws.amazon.com/about-aws/global-infrastructure/regional-product-services/
+Choose a region which has the following services available: EC2, EFS, VPS, CloudFormation, KMS, VPC, S3.
+In this tutorial, we use "Oregon(us-west-2)" as example.
 
 ## Create AWS Account and IAM Account
 
@@ -35,7 +40,8 @@ Here we will show you step by step on how to run PaddlePaddle training on AWS cl
 #### kube-aws
 
 [kube-aws](https://github.com/coreos/kube-aws) is a CLI tool to automate cluster deployment to AWS.
-
+##### Verify integrity of kube-aws downloaded
+Note: if you are using a non-official release (e.g RC release) kube-aws, you can skip this setp.
 Import the CoreOS Application Signing Public Key:
 
 ```
@@ -60,7 +66,7 @@ PLATFORM=darwin-amd64
 
 gpg2 --verify kube-aws-${PLATFORM}.tar.gz.sig kube-aws-${PLATFORM}.tar.gz
 ```
-
+##### Install kube-aws
 Extract the binary:
 
 ```
@@ -201,14 +207,15 @@ paste into following inline policies:
     ]
 }
 ```
-
+`Version` : Its value has to be exactly "2012-10-17".
 `AWS_ACCOUNT_ID`: You can get it from following command line:
 
 ```
 aws sts get-caller-identity --output text --query Account
 ```
 
-`MY_CLUSTER_NAME`: Pick a MY_CLUSTER_NAME that you like, you will use it later as well.
+`MY_CLUSTER_NAME`: Pick a MY_CLUSTER_NAME that you like, you will use it later as well. 
+Please note, stack name must satisfy regular expression pattern: [a-zA-Z][-a-zA-Z0-9*]*, which means no "_" or "-" in stack name, or kube-aws will throw error in later steps.
 
 #### External DNS name
 
@@ -216,7 +223,7 @@ When the cluster is created, the controller will expose the TLS-secured API on a
 
 The A record of that DNS name needs to be point to the cluster ip address.
 
-We will need to use DNS name later in tutorial. If you don't already own one, you can choose any DNS name (e.g., `paddle`) and modify `/etc/hosts` to associate cluster ip with that DNS name.
+We will need to use DNS name later in tutorial. If you don't already own one, you can choose any DNS name (e.g., `paddle`) and modify `/etc/hosts` to associate cluster ip with that DNS name. We will find the ip to map to `paddle` in later steps. Also in this case, will have to add name service (route53) in aws cluster in later step.
 
 #### S3 bucket
 
@@ -346,7 +353,27 @@ paddle-cl-ElbAPISe-EEOI3EZPR86C-531251350.us-west-1.elb.amazonaws.com. 59 IN A 5
 
 In the above output, both ip `54.241.164.52`, `54.67.102.112` will work.
 
-If you own a DNS name, set the A record to any of the above ip. Otherwise you can edit `/etc/hosts` to associate ip with the DNS name.
+*If you own a DNS name*, set the A record to any of the above ip. Then you can skip to the step "Access the cluster".
+
+*If you do not own a DNS name*:
+##### Update local DNS association
+Edit `/etc/hosts` to associate above ip with the DNS name.
+##### Add Route53 private name service in VPC
+ - Open Route53 web console
+ - Create hosted zone with following config
+   - Domain name: "paddle"
+   - Type: "Private hosted zone for amazon VPC"
+   - VPC ID: <Your VPC ID>
+ - Add A record
+    - Click on the zone "paddle" just created
+    - Click the button "Create record set"
+        - Name : leave blank
+        - type: "A"
+        - Value: <kube-controller's ec2 private ip>
+ - Verify name service
+    - Connect to any instance created by kube-aws via ssh
+    - Run command "host paddle", see if the ip returned is the private ip of kube-controller
+
 
 #### Access the cluster