README.md - Add more notes about installing on v4.6
README.md - Add more notes about installing on v4.6

veda-consulting/uk.co.vedaconsulting.mosaico,rocxa/uk.co.vedaconsulting.mosaico,veda-consulting/uk.co.vedaconsulting.mosaico,rocxa/uk.co.vedaconsulting.mosaico,veda-consulting/uk.co.vedaconsulting.mosaico,rocxa/uk.co.vedaconsulting.mosaico,rocxa/uk.co.vedaconsulting.mosaico,veda-consulting/uk.co.vedaconsulting.mosaico