Updated testsuite README

TESTSUITE_README

@@ -126,14 +126,21 @@ A: Obviously, the more tests succeed, the higher your grade is likely to be.
 Q: "If all test succeed, will I get a 10?"
 A: You will probably get close, but we also review code quality. If your C coding
    style is horrible, we will subtract points, even if all of the tests
-   succeed.
+   succeed. Also note that we have a number of additional tests for edge cases
+   that are not distributed to the students.
 
 Q: "I have my own testsuite, should I switch to yours instead?"
 A: Using the testsuite is not mandatory. If you have a fancy automated
-   testsuite ow your own that covers all input cases, then you can surely use
+   testsuite of your own that covers all input cases, then you can surely use
    that. Do keep in mind that we will use our own test suite to evaluate your
    compilers, so it is recommended to at run the testsuite at least once to see
    if you missed anything.
 
+Q: "Should we extend the testsuite ourselves?"
+A: By all means, we encourage you to write more tests. It is very easy to add a
+   cvc/out file pair to the functional tests directory and it saves you the
+   work of having to run your compiler on separate test files manually after
+   each small change.
+
 Q: "Does the testsuite output look awesome with fancy terminal colors?"
 A: Yes :-)