tools: add docserve target

Spaws a webserver serving the docs. Helpful to circumvent the OS
permission limitations or to access the docs form a different device on
the local network.

PR-URL: #33221
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Makefile

@@ -772,6 +772,11 @@ out/doc/api/all.json: $(apidocs_json) tools/doc/alljson.js
 docopen: $(apidocs_html)
 	@$(PYTHON) -mwebbrowser file://$(PWD)/out/doc/api/all.html
 
+.PHONY: docserve
+docserve: $(apidocs_html)
+	@$(PYTHON) -mwebbrowser http://localhost:8000/all.html
+	@$(PYTHON) -m http.server -d $(PWD)/out/doc/api
+
 .PHONY: docclean
 docclean:
 	$(RM) -r out/doc