docs: add description of example

Author: jbl428

README.md

@@ -172,6 +172,11 @@ Here is the list of options:
 
 `@ResponseBody()` will be added whenever `nest start` or `nest build` is executed.
 
+## Example
+
+There are some examples in the [example](./example) directory.
+Please refer to the [README.md](./example/README.md).
+
 ## License
 
 This library is licensed under the MIT license.

example/README.md

@@ -1,3 +1,14 @@
 # Example
 
 This is an example Nest.js project for this library.
+
+## Description
+
+This server contains two modules:
+
+- [server](./src/server): contains REST API for serving content.
+- [client](./src/client): contains REST API for calling the server API.
+
+`client` is calling `server` by using our HTTP interface library.
+
+You can find HTTP interface files whose name ends with `.http.service.ts` in [client](./src/client) module.