Updates documentation: Changes index-services.py filename to index-to-search-service.py
Updates documentation:
Changes index-services.py filename to index-to-search-service.py

Ticket:
https://trello.com/c/5oIKvS1s/100-search-service-for-briefs-plus-indexing-script

alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests