Add Changelog entry

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/ChangeLog.d/add_interruptible_sign_hash b/ChangeLog.d/add_interruptible_sign_hash
new file mode 100644
index 0000000..3d93303
--- /dev/null
+++ b/ChangeLog.d/add_interruptible_sign_hash
@@ -0,0 +1,5 @@
+Features
+   * Add an interruptible version of sign and verify hash to the PSA interface,
+     backed by internal library support for ECDSA signing and verification.
+
+