Add a link to https://gotocph.com/2019/ presentation (#4652)

Author: wing328

README.md

@@ -702,6 +702,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - 2019-11-11 - [TypeScript REST APIクライアント](https://qiita.com/unhurried/items/7b74f7d3c43545dadd2b) by [@unhurried](https://qiita.com/unhurried)
 - 2019-11-11 - [One Spec to Rule them all - OpenAPI in Action](https://www.youtube.com/watch?v=MMay_nht8ec) by [Andreas Litt](https://github.com/littldr) at [code.talks 2019](https://www.codetalks.com/)
 - 2019-11-17 - [OpenAPI Generator YouTube playlist](https://www.youtube.com/playlist?list=PLtJyHVMdzfF6fBkOUV5VDVErP23CGgHIy) at [YouTube](https://www.youtube.com)
+- 2019-11-20 - [Introduction to OpenAPI](https://noti.st/lornajane/HvDH7U/introduction-to-openapi) by [Lorna Mitchell](https://twitter.com/lornajane) at [GOTO Copenhagen 2019](https://gotocph.com/2019/)
 - 2019/11/23 - [Swagger ではない OpenAPI Specification 3.0 による API サーバー開発](https://www.slideshare.net/techblogyahoo/swagger-openapi-specification-30-api) by [Tetsuya Morimoto](https://github.com/t2y) at [JJUG CCC 2019 Fall](https://ccc2019fall.java-users.jp/)
 - 2019-11-25 - [openapi-generatorで手軽にスタブサーバとクライアントの生成](https://qiita.com/pochopocho13/items/8db662e1934fb2b408b8) by [@pochopocho13](https://twitter.com/pochopocho13)
 - 2019-11-26 - [CordaCon 2019 Highlights: Braid Server and OpenAPI Generator for Corda Client API’s](https://blog.b9lab.com/cordacon-2019-highlights-braid-server-and-openapi-generator-for-corda-flows-api-s-d24179ccb27c) by [Adel Rustum](https://blog.b9lab.com/@adelrestom) at [B9lab](https://blog.b9lab.com/)