Mosaico.setting.php - Refine title of `mosaico_layout`
Mosaico.setting.php - Refine title of `mosaico_layout`

When browsing the settings via "API Explorer", the parameter "Editor Layout"
isn't very clear.  This changes it to the more precise "Mosaico editor
layout".

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