docs: Add helper makefile

It worked for me on latest ubuntu,
and can adapter for other distros

Forwarded: https://booting.oniroproject.org/distro/oniro/-/merge_requests/375
Relate-to: https://git.ostc-eu.org/OSTC/OHOS/meta-ohos/-/merge_requests/235


Signed-off-by: Philippe Coval <philippe.coval@huawei.com>

docs/Makefile

@@ -2,9 +2,29 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+default: help all
+
+sudo ?=
+
+
 .PHONY: all
+
+help:
+	@echo "Usage: "
+	@echo "make all # to build HTML from rst sources"
+	@echo "make clean # to cleanup"
+	@echo "make setup/debian sudo=sudo # To install build tools (on debian and derived)"
+
 all:
 	sphinx-build -W . build
 
 clean:
 	rm -rf ./build
+
+setup/debian: /etc/debian_version
+	${sudo} apt-get install -y \
+make \
+python3-sphinx-tabs \
+python3-sphinxcontrib.plantuml \
+python3-dask-sphinx-theme \
+# EOL