Improve some documentation and ChangeLog entry
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 891fba6..3aa5cd6 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -199,7 +199,7 @@
* Note: this macro is available even when #MBEDTLS_CHECK_PARAMS is
* disabled, as it makes sense to check that the functions accept all
* legal values even if this option is disabled - only in that case,
- * the test if more about whether the function segfaults than about
+ * the test is more about whether the function segfaults than about
* whether it invokes MBEDTLS_PARAM_FAILED().
*
* \param TEST The test expression to be tested.