Moving React Seoul 2017 to past conferences (#304)

content/community/conferences.md

@@ -11,11 +11,6 @@ Do you know of a local React.js conference? Add it here! (Please keep the list c
 
 ## Upcoming Conferences
 
-### React Seoul 2017
-November 4 in Seoul, South Korea
-
-[Website](http://seoul.reactjs.kr/en)
-
 ### React Day Berlin
 December 2, Berlin, Germany
 
@@ -189,3 +184,9 @@ October 21 in Lagos, Nigeria
 October 25–27, Bratislava, Slovakia
 
 [Website](https://reactiveconf.com)
+
+### React Seoul 2017
+November 4 in Seoul, South Korea
+
+[Website](http://seoul.reactjs.kr/en)
+