Updated readme with some useful info.

README.md

@@ -19,6 +19,8 @@ Test methods/procs to be run are prefixed with "test" in the method/proc name. T
 
 For each suite method/proc, an implicit variable called "self" is added. This lets you access the testSuite in an OO kind of way.
 
+On failure, the macro gathers names and values of *all* arguments and functions and prints them out. It's really useful for debugging!
+
 ### Installation
 
 Install with nimble!

test.nim

@@ -64,7 +64,7 @@ testSuite TestInherit of UnitTestsNew:
 
   proc raisesOs()=
     # This proc won't be invoked as a test
-    raise newException(Exception, "Oh no! OS malfunction!")
+    raise newException(SystemError, "Oh no! OS malfunction!")
 
   method testRaises()=