Docs don't show which params are optional

[jcesarmobile]

If the type has a ?, it's not displayed, so it's not possible to know which params are optional and which ones are mandatory.

Docs should show the ? or some text that specify which one is optional and which one is mandatory.

[dtarnawsky]

The point of the PR is that if you omit the parameter then no sound is emitted. If you use '' then the default sound is emitted and if you use a value you can customize the sound.

[jcesarmobile]

Then it looks like a bug. It’s not the intended behavior.