update common usage patterns for multibar charts in docs
update common usage patterns for multibar charts in docs

puttarajubr/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,puttarajubr/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,puttarajubr/commcare-hq,qedsoftware/commcare-hq,puttarajubr/commcare-hq,qedsoftware/commcare-hq,dimagi/commcare-hq,qedsoftware/commcare-hq,qedsoftware/commcare-hq