Add changelog entry for interuptible psa key agreement APIs

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/ChangeLog.d/add-psa-iop-key-agreement.txt b/ChangeLog.d/add-psa-iop-key-agreement.txt
new file mode 100644
index 0000000..73c93d6
--- /dev/null
+++ b/ChangeLog.d/add-psa-iop-key-agreement.txt
@@ -0,0 +1,4 @@
+Features
+   * Add new psa key agreements APIs to perform key agreement
+     in an interruptible manner and return an identifier for
+     the newly created key.