Add ChangeLog entry

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/ChangeLog.d/max-record-payload-api.txt b/ChangeLog.d/max-record-payload-api.txt
new file mode 100644
index 0000000..af49fd9
--- /dev/null
+++ b/ChangeLog.d/max-record-payload-api.txt
@@ -0,0 +1,6 @@
+API changes
+   * Remove `mbedtls_ssl_get_{input,output}_max_frag_len()`
+     and add `mbedtls_ssl_get_max_in_record_payload()`,
+     complementing the existing `mbedtls_ssl_get_max_out_record_payload()`.
+     Uses of `mbedtls_ssl_get_{input,output}_max_frag_len()`
+     should be replaced by `mbedtls_ssl_get_max_{in,out}_record_payload()`.