[fuzzing] Add suggestions for a long test run

fuzzing/echidna.yaml

@@ -3,3 +3,9 @@
 testMode: "assertion"       # check that solidity asserts are never triggered
 allContracts: true          # allow calls to e.g. TestToken in test scenarios
 format: "text"              # disable interactive ui
+
+# For a longer test run, consider these options:
+# timeout: 3600               # limit test run to one hour
+# testLimit: 100000000000     # do not limit the amount of test sequences
+# stopOnFail: true            # stop on first failure
+# workers: 8                  # use more cpu cores