Docs: update ericscript install instructions
Docs: update ericscript install instructions

We don't need manual steps as it is automatically installed now
and does not require a configuration change.

vladsaveliev/bcbio-nextgen,vladsaveliev/bcbio-nextgen,chapmanb/bcbio-nextgen,a113n/bcbio-nextgen,lbeltrame/bcbio-nextgen,lbeltrame/bcbio-nextgen,biocyberman/bcbio-nextgen,biocyberman/bcbio-nextgen,lbeltrame/bcbio-nextgen,biocyberman/bcbio-nextgen,a113n/bcbio-nextgen,chapmanb/bcbio-nextgen,chapmanb/bcbio-nextgen,a113n/bcbio-nextgen,vladsaveliev/bcbio-nextgen