docs(assert) call signature of doesNotThrow should be equivalent to thro...

...ws.

The body is identical:
```
assert.throws = function(block, /*optional*/error, /*optional*/message) {
  _throws.apply(this, [true].concat(pSlice.call(arguments)));
};

// EXTENSION! This is annoying to write outside this module.
assert.doesNotThrow = function(block, /*optional*/error, /*optional*/message) {
  _throws.apply(this, [false].concat(pSlice.call(arguments)));
};
```