Generate ICS for individual event

[si]

Limit the main ICS generation (from #6) for a single event.

Name the path using a normalised event summary e.g. England v Italy becomes england-v-italy.ics

Link to the path from the Event Detail page with link text "Add to calendar"

[kevinc-cogapp]

This is likely to be a transformer plugin (https://www.gatsbyjs.org/docs/creating-a-transformer-plugin/) - this project looks helpful https://github.com/ChrisRu/f2calendar/tree/master/plugins/gatsby-transformer-ics

[si]

Good find Kevin. Will have a proper look later.