[Doc] Fix 'Murano packages structure' link
[Doc] Fix 'Murano packages structure' link

'Murano packages structure' link in Step-by-Step is broken.
This Patch fix it.

Change-Id: Ic2167c4bed1f757b67a4e224ed741c2aa5853d9b

DavidPurcell/murano_temp,NeCTAR-RC/murano,satish-avninetworks/murano,olivierlemasle/murano,olivierlemasle/murano,DavidPurcell/murano_temp,satish-avninetworks/murano,DavidPurcell/murano_temp,satish-avninetworks/murano,olivierlemasle/murano,satish-avninetworks/murano,olivierlemasle/murano,openstack/murano,NeCTAR-RC/murano,openstack/murano,NeCTAR-RC/murano,DavidPurcell/murano_temp,NeCTAR-RC/murano