ifcopenshell docs make - add server target

src/ifcopenshell-python/docs/Makefile

@@ -11,9 +11,15 @@ BUILDDIR      = _build
 # Put it first so that "make" without argument is like "make help".
 help:
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+	@echo ""
+	@echo "You can also do 'make server' to launch html server for previously built html docs."
 
 .PHONY: help Makefile
 
+server:
+	python -m http.server 8080 --directory $(BUILDDIR)/html
+.PHONY: server Makefile
+
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile