Add make serve to serve static build. (#1574)

## Description

Add `make serve` to serve static build.

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor

## Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->

## Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

docs/Makefile

@@ -1,4 +1,4 @@
-.PHONY: buildimage build dev shell check genclidocs _validatemdgen publish sync
+.PHONY: buildimage build serve dev shell check genclidocs _validatemdgen publish sync
 
 CORSO_BUILD_DIR := /tmp/.corsobuild
 CORSO_BUILD_CACHE := ${CORSO_BUILD_DIR}/cache
@@ -40,6 +40,9 @@ dockershell:
 build: genclidocs
 	$(DOCSC) npm run build
 
+serve:
+	$(DOCSC) npm run serve
+
 genclidocs: _validatemdgen ${MDGEN_BINARY}
 	@echo 'Auto-generating Corso CLI docs...'
 	$(DOCSC) rm -rf docs/cli

docs/README.md

@@ -41,6 +41,14 @@ make build
 
 This command generates static content into the `build` directory for integration with any static contents hosting service.
 
+## Serving static documentation
+
+```bash
+make serve
+```
+
+This command will serve the static content generated with `make build` at [http://localhost:3000](http://localhost:3000).
+
 ## Style and linting
 
 ```bash