Fix --testfiles README example

Author: cgewecke

README.md

@@ -73,8 +73,8 @@ npx buidler coverage --network coverage [command-options]
 ## Command Options
 | Option <img width=200/> | Example <img width=750/>| Description <img width=1000/> |
 |--------------|------------------------------------|--------------------------------|
-| file | `--file="test/registry/*.js"`    | (Truffle) Filename or glob describing a subset of JS tests to run. (Globs must be enclosed by quotes.)|
-| testfiles  | `--testfiles test/file.js` | (Buidler) JS test file(s) to run.|
+| file | `--file="test/registry/*.js"`    | (Truffle) Filename or glob describing a subset of tests to run. (Globs must be enclosed by quotes.)|
+| testfiles  | `--testfiles="test/registry/*.ts"` | (Buidler) Test file(s) to run. (Globs must be enclosed by quotes.)|
 | solcoverjs | `--solcoverjs ./../.solcover.js` | Relative path from working directory to config. Useful for monorepo packages that share settings. (Path must be "./" prefixed) |
 | network    | `--network development` | Use network settings defined in the Truffle or Buidler config |
 | temp[<sup>*</sup>][14]       | `--temp build`   | :warning: **Caution** :warning:  Path to a *disposable* folder to store compilation artifacts in. Useful when your test setup scripts include hard-coded paths to a build directory. [More...][14] |