Add note about 'make test' issue

README.md

@@ -66,6 +66,10 @@ You can also run our humble test suite (~10 seconds):
 
     make test
 
+NOTE that  the `make test` actually tests the version of Shellfu
+*installed* on your machine.  This is a known issue, sorry for
+that.
+
 
 Usage
 -----