[readme] Update the documention for t.doesNotThrow()

readme.markdown

@@ -336,9 +336,10 @@ Please note that the second parameter, `expected`, cannot be of type `string`. I
 
 ## t.doesNotThrow(fn, expected, msg)
 
-Assert that the function call `fn()` does not throw an exception. `expected`, if present, limits what should not be thrown, and must be a `RegExp` or `Function`. 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 fail  only if the string representation of the exception contains the word `user`. Any other exception will result in a passed test.  The `Function` is the exception thrown (e.g. `Error`).  If `expected` is not of type `RegExp` or `Function`, or omitted entirely, any exception will result in a failed test. `msg` is an optional description of the assertion.
+Assert that the function call `fn()` does not throw an exception. `expected` is ignored unless it is a value of type `string`. Any exception will result in a failed test. `msg` is an optional description of the assertion.
+
+Please note that the second parameter, `expected`, cannot be of type `string`. If a value of type `string` is provided for `expected`, then `t.doesNotThrows(fn, expected, msg)`  will execute, but the value of `expected` will be set to  `undefined`, and the specified string will be set as the value for the `msg` parameter (regardless of what _actually_ passed as the third parameter).
 
-Please note that the second parameter, `expected`, cannot be of type `string`. If a value of type `string` is provided for `expected`, then `t.doesNotThrows(fn, expected, msg)`  will execute, but the value of `expected` will be set to  `undefined`, and the specified string will be set as the value for the `msg` parameter (regardless of what _actually_ passed as the third parameter). This can cause unexpected results, so please be mindful.
 ## t.test(name, [opts], cb)
 
 Create a subtest with a new test handle `st` from `cb(st)` inside the current test `t`. `cb(st)` will only fire when `t` finishes. Additional tests queued up after `t` will not be run until all subtests finish.