[FIX] [DOC] make it explicit that the module name is mandatory when specifying...

[FIX] [DOC] make it explicit that the module name is mandatory when specifying a sub view via the context

lp bug: https://launchpad.net/bugs/1214799 fixed

bzr revid: alexandre.fayolle@camptocamp.com-20130821094913-2frk2550b4szka5s