Add DOCUMENTS_URL to config
Add DOCUMENTS_URL to config

Used to build the full asset URL for uploaded documents

mtekel/digitalmarketplace-admin-frontend,mtekel/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend,mtekel/digitalmarketplace-admin-frontend,mtekel/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend,alphagov/digitalmarketplace-admin-frontend