update link to sigmod 2021

Signed-off-by: Bertty Contreras-Rojas <bertty@scalytics.io>
diff --git a/_publications/2021-06-21-sigmod.md b/_publications/2021-06-21-sigmod.md
index f7038f9..05d4649 100644
--- a/_publications/2021-06-21-sigmod.md
+++ b/_publications/2021-06-21-sigmod.md
@@ -24,7 +24,7 @@
 year: 2021
 month: 06
 day: 20
-link-paper: https://www.researchgate.net/publication/350021175_The_Power_of_Nested_Parallelism_in_Big_Data_Processing_--_Hitting_Three_Flies_with_One_Slap
+link-paper: https://www.agora-ecosystem.com/publications/nested/
 link-external: true
 ---