Updated Changelog (markdown)

Changelog.md

@@ -13,9 +13,9 @@ Older versions are at the bottom of this page.
 
 ## 4.3.2018
 
-* Form for assigning exercise in multiple groups simultaneously was debugged and enabled.
+* Form for assigning exercise in multiple groups at once was debugged and enabled.
 * External accounts (accounts mapped to SIS accounts) are prevented from changing their names.
-* Supervisors may delete submitted solutions of the students.
+* Supervisors may delete solutions submitted by the students.
 
 ## 26.2.2018