Add ccache-swig hash fix to RELEASENOTES
diff --git a/RELEASENOTES b/RELEASENOTES
index ee5bde6..493f199 100644
--- a/RELEASENOTES
+++ b/RELEASENOTES
@@ -9,6 +9,7 @@
 
 SWIG-4.1.1 summary:
 - Couple of stability fixes.
+- Stability fix in ccache-swig when calculating hashes of inputs.
 - Some template handling improvements.
 - R - minor fixes plus deprecation for rtypecheck typemaps being optional.