[readme] improve t.throws description for Function

readme.markdown

@@ -327,7 +327,7 @@ Aliases: `t.notLooseEqual()`, `t.notLooseEquals()`
 
 ## t.throws(fn, expected, msg)
 
-Assert that the function call `fn()` throws an exception. `expected`, if present, must be a `RegExp`, `Function`, or `Object`. The `RegExp` matches the string representation of the exception, as generated by `err.toString()`. For example, if you set `expected` to `/user/`, the test will pass only if the string representation of the exception contains the word `user`. Any other exception will result in a failed test. The `Function` is the exception thrown (e.g. `Error`). `Object` in this case corresponds to a so-called validation object, in which each property is tested for strict deep equality. As an example, see the following two tests--each passes a validation object to `t.throws()` as the second parameter. The first test will pass, because all property values in the actual error object are deeply strictly equal to the property values in the validation object.
+Assert that the function call `fn()` throws an exception. `expected`, if present, must be a `RegExp`, `Function`, or `Object`. The `RegExp` matches the string representation of the exception, as generated by `err.toString()`. For example, if you set `expected` to `/user/`, the test will pass only if the string representation of the exception contains the word `user`. Any other exception will result in a failed test. The `Function` could be the constructor for the Error type thrown, or a predicate function to be called with that exception. `Object` in this case corresponds to a so-called validation object, in which each property is tested for strict deep equality. As an example, see the following two tests--each passes a validation object to `t.throws()` as the second parameter. The first test will pass, because all property values in the actual error object are deeply strictly equal to the property values in the validation object.
 ```
     const err = new TypeError("Wrong value");
     err.code = 404;