Add React Case Study Festival 2021 (#3553)

* Update conferences.md

* Update conferences.md

Co-authored-by: Alexey Pyltsyn <lex61rus@gmail.com>

content/community/conferences.md

@@ -17,16 +17,16 @@ March 27, 2021 - remote event
 
 [Website](https://fwdays.com/en/event/react-fwdays-2021) - [Twitter](https://twitter.com/fwdays) - [Facebook](https://www.facebook.com/events/1133828147054286) - [LinkedIn](https://www.linkedin.com/events/reactfwdays-21onlineconference6758046347334582273) - [Meetup](https://www.meetup.com/ru-RU/Fwdays/events/275764431/)
 
-### React Next 2020 {#react-next-2020}
-December 1-2, 2020 - remote event
-
-[Website](https://react-next.com/) - [Twitter](https://twitter.com/reactnext) - [Facebook](https://www.facebook.com/ReactNext2016/)
-
 ### React Summit - Remote Edition 2021 {#react-summit-remote-2021}
 April 14-16, 2021, 7am PST / 10am EST / 4pm CEST - remote event
 
 [Website](https://remote.reactsummit.com) - [Twitter](https://twitter.com/reactsummit) - [Facebook](https://www.facebook.com/reactamsterdam) - [Videos](https://youtube.com/c/ReactConferences)
 
+### React Case Study Festival 2021 {#react-case-study-festival-2021}
+April 27-28, 2021 - remote event
+
+[Website](https://react.geekle.us/) - [LinkedIn](https://www.linkedin.com/events/reactcasestudyfestival6721300943411015680/) - [Facebook](https://www.facebook.com/events/255715435820203) 
+
 ### render(ATL) 2021 {#render-atlanta-2021} 
 September 13-15, 2021. Atlanta, GA, USA
 
@@ -39,6 +39,11 @@ November 12-13, 2021 in Mumbai, India
 
 ## Past Conferences {#past-conferences}
 
+### React Next 2020 {#react-next-2020}
+December 1-2, 2020 - remote event
+
+[Website](https://react-next.com/) - [Twitter](https://twitter.com/reactnext) - [Facebook](https://www.facebook.com/ReactNext2016/)
+
 ### React Conf Brasil 2020 {#react-conf-brasil-2020}
 November 21, 2020 - remote event