shared-signals.adoc: Replace ValueSignal with SharedValueSignal

[DarioViva42]

This documentation describes the usage of Shared Signals. So it is really confusing and probably a mistake, that in some of the examples Local Signals are used.

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[DarioViva42]

Also what I also find pretty Strange that there is a Shared Signal SharedNumberSignal but not a Local Signal NumberSignal. There are also similar discrepancies in this regard. It's especially strange because in an earlier edition of Signals the class NumberSignal existed. Is there a migration guide for people that used the Signals as they were in the early days?

Also we get the following error:

An asynchronous signal can only share transaction with computed signals and other asynchronous signals that belong to the same tree.

Beforehand this code worked.

We had two Signals that we created with the IN_MEMORY_SHARED SignalFactory. and then we updated the two signals with Signal.runInTransaction. This worked but now it does no longer.

Where should such questions be asked. On some documentation pages you can comment. Like https://vaadin.com/docs/latest/components/avatar. But on the documentation https://vaadin.com/docs/latest/flow/ui-state/shared-signals this does not work, which is kind of strange.