Update README.md

README.md

@@ -396,6 +396,7 @@ This has the following structure:
 | `--random-seed`       | use a random seed. Note this overrides any value specified by `--seed`                                                       |
 | `--contract`          | specify a specific contract name to mutate; by default mutate all contracts                                                  |
 | `--functions`         | specify one or more functions to mutate; by default mutate all functions                                                     |
+| `--mutations`         | specify one or more mutation operators to use; only generates mutants that are created using the specified operators         |
 
 Gambit also supports _pass-through arguments_, which are arguments that are
 passed directly to solc. All pass-through arguments are prefixed with `solc-`:
@@ -436,4 +437,4 @@ for their excellent contributions to an earlier prototype of Gambit.
 
 
 [config-examples]: https://github.com/Certora/gambit/blob/master/benchmarks/config-jsons/
-[test6]: https://github.com/Certora/gambit/blob/master/benchmarks/config-jsons/test6.json
+[test6]: https://github.com/Certora/gambit/blob/master/benchmarks/config-jsons/test6.json