Adding React Helsinki meetup (#7474)

* Update meetups.md

Added React Helsinki to meetups.

* Update meetups.md

Author: hencca

src/content/community/meetups.md

@@ -57,6 +57,9 @@ Do you have a local React.js meetup? Add it here! (Please keep the list alphabet
 * [React Advanced London](https://guild.host/react-advanced-london)
 * [React Native London](https://guild.host/RNLDN)
 
+## Finland {/*finland*/}
+* [Helsinki](https://www.meetabit.com/communities/react-helsinki)
+
 ## France {/*france*/}
 * [Lille](https://www.meetup.com/ReactBeerLille/)
 * [Paris](https://www.meetup.com/ReactJS-Paris/)