Add ChangeLog entry

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/ChangeLog.d/ssl-error-code-cleanup.txt b/ChangeLog.d/ssl-error-code-cleanup.txt
new file mode 100644
index 0000000..0438aa2
--- /dev/null
+++ b/ChangeLog.d/ssl-error-code-cleanup.txt
@@ -0,0 +1,7 @@
+API changes
+   * Remove SSL error codes `MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED`
+     and `MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH` which are never
+     returned from the public SSL API.
+   * Remove `MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE` and return
+     `MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL` instead.
+     `