Added README to spring boot sample to address #127.

Author: sapessi

samples/springboot/pet-store/README.md

@@ -0,0 +1,62 @@
+# Serverless Spring Boot example
+A basic pet store written with the [Spring Boot framework](https://projects.spring.io/spring-boot/). The `LambdaHandler` object is the main entry point for Lambda.
+
+The application can be deployed in an AWS account using the [Serverless Application Model](https://github.com/awslabs/serverless-application-model). The `sam.yaml` file in the root folder contains the application definition
+
+## Installation
+To build and install the sample application you will need [Maven](https://maven.apache.org/) and the [AWS CLI](https://aws.amazon.com/cli/) installed on your computer.
+
+In a shell, navigate to the sample's folder and use maven to build a deployable jar.
+```
+$ mvn package
+```
+
+This command should generate a `serverless-spring-boot-example-1.0-SNAPSHOT.jar` in the `target` folder. Now that we have generated the jar file, we can use the AWS CLI to package the template for deployment. 
+
+You will need an S3 bucket to store the artifacts for deployment. Once you have created the S3 bucket, run the following command from the sample's folder:
+
+```
+$ aws cloudformation package --template-file sam.yaml --output-template-file output-sam.yaml --s3-bucket <YOUR S3 BUCKET NAME>
+Uploading to xxxxxxxxxxxxxxxxxxxxxxxxxx  6464692 / 6464692.0  (100.00%)
+Successfully packaged artifacts and wrote output template to file output-sam.yaml.
+Execute the following command to deploy the packaged template
+aws cloudformation deploy --template-file /your/path/output-sam.yaml --stack-name <YOUR STACK NAME>
+```
+
+As the command output suggests, you can now use the cli to deploy the application. Choose a stack name and run the `aws cloudformation deploy` command from the output of the package command.
+ 
+```
+$ aws cloudformation deploy --template-file output-sam.yaml --stack-name ServerlessSpringBootSample --capabilities CAPABILITY_IAM
+```
+
+Once the application is deployed, you can describe the stack to show the API endpoint that was created. The endpoint should be the `SpringBootPetStoreApi` key of the `Outputs` property:
+
+```
+$ aws cloudformation describe-stacks --stack-name ServerlessSpringBootSample
+{
+    "Stacks": [
+        {
+            "StackId": "arn:aws:cloudformation:us-west-2:xxxxxxxx:stack/JerseySample/xxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxx", 
+            "Description": "Example Pet Store API written with spark with the aws-serverless-java-container library", 
+            "Tags": [], 
+            "Outputs": [
+                {
+                    "Description": "URL for application", 
+                    "OutputKey": "SpringBootPetStoreApi", 
+                    "OutputValue": "https://xxxxxxx.execute-api.us-west-2.amazonaws.com/Prod/pets"
+                }
+            ], 
+            "CreationTime": "2016-12-13T22:59:31.552Z", 
+            "Capabilities": [
+                "CAPABILITY_IAM"
+            ], 
+            "StackName": "JerseySample", 
+            "NotificationARNs": [], 
+            "StackStatus": "UPDATE_COMPLETE"
+        }
+    ]
+}
+
+```
+
+Copy the `OutputValue` into a browser to test a first request.