[Bug/Research]: Toast timeout minimum differs from design docs

### Code of conduct

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### Description of issue

Need confirmation on truth
[Toast design specs](https://spectrum.adobe.com/page/toast/) state that the minimum for "auto-dismissible" (timeout) should be a minimum of 5s (5000ms)
[Toast web component storybook](https://opensource.adobe.com/spectrum-web-components/storybook/index.html?path=/story/toast--default) sets the minimum to 6s (6000ms) in the timeout if any number under 6000 is provided.

Also there is additional accessibility notes about word count and adding time. Where can i find that specific documentation?

Quick fix:
- Update the docs or the timeout minimum to align

Future version improvement:
Should we programmatically set the timeout time based on word count from the content slot? I ask this because its odd to be able to set a property value under 6000ms and it be defaulted to that. Gives me a dark pattern vibe i dont like.

i.e. the property type could be boolean like defined in the design docs and the consumer doesnt have to be concerned with timing values, that comes for free with our accessibility requirements (note: this is a change to the API and would be something to consider for V2.0)

Start by comparing the linked Toast design specs with the Toast web component Storybook timeout behavior and accessibility notes. Confirm which minimum is authoritative, then identify whether the docs or timeout behavior should change; done means the documented and implemented minimums agree and the relevant accessibility guidance is linked.

Written by the indexing model from the issue text.