[LiveComponent][Doc] Update Live Components docs for reusable bundles

[javiereguiluz]

Q	A
Bug fix?	no
New feature?	no
Docs?	no
Issues	-
License	MIT

I lost a lot of time when trying to make a Live Component inside a reusable bundle work. I could only fix it when looking at how other budnles solved it (e.g. https://github.com/Mezcalito/ux-search/blob/9e34a01707d4c09e7538e35b6e8549f3722e0ca4/config/services.php#L62-L78).

So, I propose to add some docs explaining how to do it.

[Kocal]

I'm not sure about this one, it feels super hacky since it relies on internals structure.

Is there a better alternative? note that Symfony\UX\LiveComponent\Attribute\AsLiveComponent::serviceConfig() exists but that's still internal. cc @kbond @smnandre

[smnandre]

We would like to open this up more, but every step towards opening is met with abuse, so that’s not encouraging…

But, as @Kocal politely said, it’s a no-go to document the internal (and soon-to-change) component-registration mechanism.

The Mezcalito team already knows this can change, and I would strongly advise anyone against using internal definitions to register services (LiveComponent or ... any Symfony component).

Also, as always, we’re not many around here (and none of us is paid to work on Symfony), so things move slowly…

I’m closing this PR to avoid exposing something we don’t want people to feel frustrated about if when it changes… but rest assured we also have this in mind—just lacking time to implement new ideas/better methods.