Feedback on tutorial (from a beginner's perspective)

Total elixir newbie here (so my ignorance is pretty high, but maybe this is a useful perspective).

> Invoking CounterWeb.Endpoint.broadcast_from sends a message from the current process self() on the @topic, the key is "inc" and the value is the new_state.assigns Map.

I think for people coming from other languages/frameworks it's a bit confusing to mention that the key is `"inc"`. I don't see that key pop up anywhere else after that, or see how the `"inc"` value is relevant. It looks like the new state of `:val` is already set and sent to the topic. Is it going to call `handle_event("inc", ...)` again? It doesn't look like it, it seems like `handle_info(...)` is going to update `assigns` for all the connected clients.

To put the question another way, why should I pass `"inc"` instead of `"foo"`?

Everything else is clear, but that's the one bit that doesn't make sense.

Start with the tutorial passage describing CounterWeb.Endpoint.broadcast_from and read the surrounding LiveView broadcast and handle_info explanation. Clarify why the "inc" key is used, or state whether it is arbitrary, so a beginner can understand the message flow; the issue does not name a file or test.

Written by the indexing model from the issue text.