Update 2.15.2 release notes

Change-Id: I29420b245b81f2b3a0fe8c8a0ad105424d1602ab
diff --git a/releases/2.15.md b/releases/2.15.md
index 7c21a80..9fe0ae6 100644
--- a/releases/2.15.md
+++ b/releases/2.15.md
@@ -355,6 +355,12 @@
 
 ### 2.15.2 *(in development)* {#2.15.2}
 
+* [Issue 8742](https://bugs.chromium.org/p/gerrit/issues/detail?id=8742):
+Fix infinite loop in intraline diff loader.
+
+  A regression introduced in 2.15.1 caused excessive CPU usage when loading
+  intraline diffs.
+
 * [Issue 8697](https://bugs.chromium.org/p/gerrit/issues/detail?id=8697):
 Restore the ability to ignore invalid review labels.