Clarifications about nested live views and their appropriate use (#3713)

* Add hint about find_live_child/2 to the live_render docs.

* Add a recommendation to try LiveComponent before resorting to a liveview.

* Apply suggestions from code review

* Update lib/phoenix_component.ex

---------

Co-authored-by: Steffen Deusch <[email protected]>

Author: jdmarshall

lib/phoenix_component.ex

@@ -946,6 +946,9 @@ defmodule Phoenix.Component do
 
   * When rendering a LiveView inside a regular (non-live) controller/view.
 
+  Most other cases for shared functionality, including state management and user interactions, can be
+  [achieved with function components or LiveComponents](welcome.html#compartmentalize-state-markup-and-events-in-liveview)
+
   ## Options
 
   * `:session` - a map of binary keys with extra session data to be serialized and sent
@@ -1011,6 +1014,11 @@ defmodule Phoenix.Component do
   Beware if you set this to `:body`, as any content injected inside the body
   (such as `Phoenix.LiveReload` features) will be discarded once the LiveView
   connects
+
+  ## Testing
+
+  Note that `render_click/1` and other testing functions will send events to the root LiveView, and you will want to
+  `find_live_child/2` to interact with nested LiveViews in your live tests.
   """
   def live_render(conn_or_socket, view, opts \\ [])