Possible mistake in /content/docs/usage/observable.mdx

[SzymonNastaly]

I have just started learning legend-state. I think I found a small mistake in the documentation:
Right now str$ is not used anywhere in the linked observable. Shouldn't the instances of arr$ be replaced with str$?

legend-docs/packages/state/src/content/docs/usage/observable.mdx

Lines 257 to 265 in f99d395

	Or it could be used to automatically deserialize/serialize a string value.
	```js
	const str$ = observable('[1,2,3]')
	const arr$ = observable(linked({
	get: () => JSON.parse(arr$.get())
	set: (value) => arr$.set(JSON.stringify(value))
	}))
	```

[jmeistrich]

Thanks! Fixed, and will publish an update to the site shortly!