README.md: Add rauc-hawkbit-updater to the list of clients supporting hawkBit (#1181)
README.md: Add rauc-hawkbit-updater to the list of clients supporting hawkBit (#1181)

Also add the word 'demo' to the python variant to give a hint to not use
this for real-world applications.

Signed-off-by: Enrico Joerns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>
bsinno/hawkbit,eclipse/hawkbit,bsinno/hawkbit,eclipse/hawkbit,bsinno/hawkbit,eclipse/hawkbit,eclipse/hawkbit