Add changelog entry for new mbedtls_pkcs5_pbe2_ext function

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/ChangeLog.d/add-new-pkcs5-pbe2-ext-fun.txt b/ChangeLog.d/add-new-pkcs5-pbe2-ext-fun.txt
new file mode 100644
index 0000000..1ab8640
--- /dev/null
+++ b/ChangeLog.d/add-new-pkcs5-pbe2-ext-fun.txt
@@ -0,0 +1,6 @@
+Features
+   * Add new mbedtls_pkcs5_pbes2_ext function a more secure replacement to
+     mbedtls_pkcs5_pbes2 function because it reports the length of the output
+     bytes written to the output buffer and it requires a parameter containing
+     the output buffer size and validate if the output buffer is big enough
+     for output including padding.