chore: add readme for example

Author: tmokmss

README.md

@@ -56,7 +56,7 @@ Then, the extracted directories will be located as the following:
 └── module1               # extracted module1 assets
 ```
 
-Please check https://github.com/tmokmss/deploy-time-build/tree/main/example for a complete example.
+Please check [example directory](./example/) for a complete example. 
 
 ## Why do we need this construct?
 Previously, there are a few different ways to deploy frontend applications from CDK (1 and 2 below). But none is perfect with different pros and cons. This construct adds another option to deploy frontend apps.

example/README.md

@@ -1,9 +1,16 @@
 ## How to Deploy
 ```sh
-# Assume current direcotry is the example directory
+# Assume current directory is the example directory
 cd ../src/lambda/nodejs-build
 npm ci
 npm run build
 cd -
 npx cdk deploy
 ```
+
+## Description
+After a successfull deployment, you will get a CloudFront URL from the stack output.
+
+![demo](../imgs/demo.png)
+
+You can see the API endpoint is successfully injected to the sample frontend app.