Added a note about client versions for reproducing the bug (#31)

examples/ConstantinopleGasUsage/README.md

@@ -15,4 +15,9 @@ This example uses [Echidna](https://github.com/trailofbits/echidna), a
 property-based fuzzer, so results are nondeterminstic. But generally
 running this example should result in at least one failed differential
 test. You can get additional details of the transaction that triggered
-the bug by examining `log/DifferentialTester/GAS_USAGE/FAILED.log`.
+the bug by examining `log/DifferentialTester/GAS_USAGE/FAILED.log`.
+
+Note that this example was tested with Geth 1.8.17-stable and Parity
+v2.0.8-stable. Newer versions of these clients will likely have
+patched the Constantinople consensus bug and Etheno's differential
+tester will therefore pass all tests.