doc: fix typo in test.md · nodejs/node@ef413b5

coverage does not reach the threshold specified, the process will exit with code `1`.

**Default:** `0`.

* `env` {Object} Specify environment variables to be passed along to the test process.

This options is not compatible with `isolation='none'`. These variables will override

This option is not compatible with `isolation='none'`. These variables will override

those from the main process, and are not merged with `process.env`.

**Default:** `process.env`.

* Returns: {TestsStream}