Update discord link (#13)

Co-authored-by: n3parikh <n3parikh@localhost>
Reviewed-on: #13
Co-authored-by: n3parikh <n3parikh@csclub.uwaterloo.ca>
Co-committed-by: n3parikh <n3parikh@csclub.uwaterloo.ca>

ceod/model/templates/welcome_message.j2

@@ -11,7 +11,7 @@ You can hear about upcoming events in a number of ways:
 * Check our website from time to time: http://csclub.uwaterloo.ca/
 * Subscribe to our events calendar feed: http://csclub.uwaterloo.ca/events.ics
 * Like the CSC on Facebook: https://www.facebook.com/uw.computerscienceclub
-* Join the CSC Discord server: https://discord.gg/uwcsclub
+* Join the CSC Discord server: https://discord.gg/pHfYBCg
 * Read your email: announcements are sent via the csc-general mailing list
 * Keep an eye out in the MC: posters for upcoming events appear in stairwells and hallways