docs: Finalize iperf-3.10 release date.
diff --git a/RELNOTES.md b/RELNOTES.md
index 8ec26c7..8bc5b33 100644
--- a/RELNOTES.md
+++ b/RELNOTES.md
@@ -1,7 +1,7 @@
 iperf3 Release Notes
 ====================
 
-iperf 3.10 2021-05-xx
+iperf 3.10 2021-05-26
 ---------------------
 
 * Notable user-visible changes