[ncpc2021] update registration info

Author: exoji2e

_events/2021-10-09-ncpc.md

@@ -13,7 +13,7 @@ The [Nordic Collegiate Programming Contest](https://nordic.icpc.io/ncpc2021) (NC
 
 ### Registration
 
-The [registration system](https://icpc.global/regionals/finder/Nordic-2021) will soon open.
+The [registration](https://icpc.global/regionals/finder/Nordic-2021) is open! Register your team by the 7th of October.
 
 Each team member needs an account in the [ICPC registration system](https://icpc.global/). However the team should only be registered once by one member.