Improve changelog for ECDSA verify fix

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/ChangeLog.d/ecdsa-verify-fixes.txt b/ChangeLog.d/ecdsa-verify-fixes.txt
index 6dbd470..166f91e 100644
--- a/ChangeLog.d/ecdsa-verify-fixes.txt
+++ b/ChangeLog.d/ecdsa-verify-fixes.txt
@@ -1,5 +1,5 @@
 Bugfix
-   * Fix ECDSA verification, where it was failing to validate the public key
-     for signatures where R == 1 and S == 1. This bug meant that it was
-     possible to verify such signatures with an invalid public key, in some
-     cases.
+   * Fix ECDSA verification, where it was not always validating the
+     public key. This bug meant that it was possible to verify a
+     signature with an invalid public key, in some cases. Reported by
+     Guido Vranken in #4420.