Add example for mocha 7, since they removed some watch flags in v7 (#961

)

* Add example for mocha 7, since they removed some watch flags in v7

* addressing pr feedback

* empty commit to trigger travis re-run

README.md

@@ -54,12 +54,20 @@ You can require `ts-node` and register the loader for future requires by using `
 
 ### Mocha
 
+Mocha 6
+
 ```sh
 mocha --require ts-node/register --watch-extensions ts,tsx "test/**/*.{ts,tsx}" [...args]
 ```
 
 **Note:** `--watch-extensions` is only used in `--watch` mode.
 
+Mocha 7
+
+```sh
+mocha --require ts-node/register --extensions ts,tsx --watch --watch-files src 'tests/**/*.{ts,tsx}' [...args]
+```
+
 ### Tape
 
 ```sh