rose documentation: fix strict validation of rose date tutorial
metomi/rose#687: fix no suites at all
Merge pull request #705 from benfitzpatrick/doc.fix-rose-date-tutorial

rose documentation: fix strict validation of rose date tutorial
Merge pull request #706 from benfitzpatrick/687.fix-no-suites-rosie-go

metomi/rose#687: fix no suites at all