Update CODEOWNERS for new team name (#67)

nhs-notify-config -> nhs-notify-client-config

Author: m-houston

.github/CODEOWNERS

@@ -1,7 +1,7 @@
 # NHS Notify Code Owners
 
 # Notify default owners
-*                           @NHSDigital/nhs-notify-config
+*                           @NHSDigital/nhs-notify-client-config
 
 /.github/                   @NHSDigital/nhs-notify-admins
 *.code-workspace            @NHSDigital/nhs-notify-admins