Merge pull request #3552 from dfinity/raw-icp0-example

add: `raw.icp0` local example

docs/developer-docs/web-apps/application-frontends/default-frontend.mdx

@@ -35,7 +35,17 @@ When a dapp is deployed to ICP and has a frontend configured, the frontend asset
 
 For canisters deployed to the mainnet, the canister can be accessed in a web browser using the canister's ID followed by `.ic0.app`, `.icp0.io` or `raw.icp0.io`. For example, the [playground](https://m7sm4-2iaaa-aaaab-qabra-cai.ic0.app/) is an application with a frontend user interface that can be used to deploy canisters in a temporary, sandbox environment. This dapp can be accessed via the URL `https://m7sm4-2iaaa-aaaab-qabra-cai.ic0.app/`.
 
-The `raw.icp0.io` domain is used for canisters deployed to the mainnet, and provides a way to access the raw HTTP interface of that canister. For local deployments that want to simulate the behavior of the `raw.icp0.io` domain, you must implement a method in your canister that consumes an HTTP request and outputs an HTTP response.
+The `raw.icp0.io` domain is used for canisters deployed to the mainnet, and provides a way to access the raw HTTP interface of that canister. For local deployments that want to simulate the behavior of the `raw.icp0.io` domain, you must implement a method in your canister that consumes an HTTP request and outputs an HTTP response. Here is an example written in Motoko:
+
+```motoko no-repl
+public shared(msg) func http_request(req: HttpRequest) : async HttpResponse {
+    {
+        status = { code = 200; reason = "OK" };
+        headers = [( "Content-Type", "text/plain" )];
+        body = Text.encodeUtf8("Hello, World!");
+    }
+};
+```
 
 By default, projects created with `dfx new` have the option to include a frontend canister that uses a template for one of several frontend frameworks. This guide illustrates using the default React template generated by `dfx new` and guides you through some basic modifications to customize the interface displayed.