Fix ChangeLog format

Signed-off-by: Ben Taylor <ben.taylor@linaro.org>
diff --git a/ChangeLog.d/remove_mbedtls_pk_type.txt b/ChangeLog.d/remove_mbedtls_pk_type.txt
index 0ad38e0..4b33d1e 100644
--- a/ChangeLog.d/remove_mbedtls_pk_type.txt
+++ b/ChangeLog.d/remove_mbedtls_pk_type.txt
@@ -1,4 +1,3 @@
-
 Removals
    * Remove mbedtls_pk_type_t from the public interface and replace it with
      mbedtls_pk_sigalg_t.