docs(eslint-plugin): add docs for signal-state-no-arrays-at-root-level

[iErKy]

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PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
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[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Closes #4501

What is the new behavior?

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[ ] Yes
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[timdeschryver]

Thanks for the PR @iErKy .
You can ignore the failing build, this is something not related to this PR.

[timdeschryver]

Suggested change

	This rule ensure that a Signal State shouldn't accept an array type at root level.
	This rule ensure that a Signal State shouldn't accept an array type at the root level.

[timdeschryver]

Formatting:

Suggested change

	```ts
	```ts

[timdeschryver]

Formatting:

Suggested change

	```ts
	const store = withState([1, 2, 3]);
	```
	```ts
	const store = withState([{ foo: 'bar' }]);
	```
	```ts
	const store = withState<string[]>([]);
	```
	```ts
	const initialState = [];
	const store = withState(initialState);
	```
	```ts
	const store = withState([1, 2, 3]);

const store = withState([{ foo: 'bar' }]);

const store = withState<string[]>([]);

const initialState = [];
const store = withState(initialState);

[iErKy]

@timdeschryver will fix comments and push changes.

[timdeschryver]

Thanks @iErKy