Improve test docs according to suggestion

exercises/concept/lasagna/LasagnaTest.php

@@ -6,10 +6,10 @@
  * We use `assertEquals()` here for its loose type checking. We don't care if
  * the student returns numeric strings or integers in this exercise.
  *
- * - Please use `assertSame()` whenever possible. Note reasons for exceptions.
+ * - Please use `assertSame()` whenever possible. Add a comment when it is not possible.
  * - Use calls with named arguments only when the exercise supplies method stubs with argument names.
  *   These can help students to understand things, but can also be in the way of defining argument names
- *   the students wants (e.g. in their native language).
+ *   the students want (e.g. in their native language).
  * - Add @testdox with a useful test title, e.g. the task heading from `instructions.md`.
  *   The online editor shows that to students.
  * - Add fail messages to assertions where helpful to tell students more than @testdox says.