docs: Add suggestions about getInitialState on persist

[Cadienvan]

The persist middleware alters the behavior of getInitialState because of internal reasons mentioned in #2277.
When following the documentation here while having a persisted state accompanied by a non-persisted one, the suggestion about getInitialState in the vite's afterEach lifecycle method isn't applicable.

Here's an example:

Our service slice is persisted, while the remaining 3 aren't, so our getInitialState will only contain the createServiceSlice slice of the state.

I'd love to mention it in a PR if you have any idea about how to properly handle this.

[dai-shi]

@dbritto-dev ?

[Cadienvan]

That's what I imagined, in fact I agree with the proposed resolution, I'd just mention it in the documentation.

[dbritto-dev]

@Cadienvan actually any middleware works at store level but people use to misunderstand that and try to use it on slices

[Cadienvan]

@dbritto-dev so do you think adding a line here mentioning middlewares should not be used at the slice level isn't necessary?

Of course, mine is only a suggestion but I'd love to be of help being in a team which had such an issue and didn't find info about it.

[dbritto-dev]

@Cadienvan no I don't, I'm down with you we shall add a note to make it more clear

[dbritto-dev]

@Cadienvan let's create a PR I would be happy to review it