README: Write "Serve" instructions

Author: kj4ezj

README.md

@@ -21,6 +21,7 @@ You can see it live at [https://stake.eosnetwork.com](https://stake.eosnetwork.c
     1. [Prerequisites](#prerequisites)
     1. [Initialization](#initialization)
     1. [Build](#build)
+    1. [Serve](#serve)
 1. [See Also](#see-also)
 
 <!-- contents markdown end -->
@@ -70,6 +71,15 @@ yarn build
 ```
 The "build" generates a `build` folder in the root of the repo that can be uploaded directly to AWS S3 using the web console, AWS CLI, or with something like ~~Terraform~~ Tofu.
 
+### Serve
+Running this...
+```bash
+yarn serve
+```
+...uses [Caddy](https://caddyserver.com) in `file_server` mode to publish the build artifacts in the `build` folder in the root of the repo at port `8443` to emulate an S3 bucket. You can load this in your browser by nativating to [https://localhost:8443](https://localhost:8443).
+
+Press `[Ctrl]` + `[C]` to stop the server.
+
 ## See Also
 More resources.
 - [aws-cloudwatch-alarm-handler](https://github.com/eosnetworkfoundation/aws-cloudwatch-alarm-handler) lambda