Clarify docs, closes #13666

Author: josevalim

lib/ex_unit/lib/ex_unit/callbacks.ex

@@ -538,15 +538,13 @@ defmodule ExUnit.Callbacks do
   test, as simply shutting down the process would cause it to be restarted
   according to its `:restart` value.
 
-  Another advantage is that the test process will act as both an ancestor
-  as well as a caller to the supervised processes. When a process is started
-  under a supervision tree, it typically populates the `$ancestors` key in
-  its process dictionary with all of its ancestors, which will include the test
-  process. Additionally, `start_supervised/2` will also store the test process
-  in the `$callers` key of the started process, allowing tools that perform
-  either ancestor or caller tracking to reach the test process. You can learn
-  more about these keys in
-  [the `Task` module](`Task#module-ancestor-and-caller-tracking`).
+  Finally, since Elixir v1.17.0, the test supervisor has both `$ancestors`
+  and `$callers` key in its process dictionary pointing to the test process.
+  This means developers can invoke `Process.get(:"$callers", [])` in their
+  `start_link` function and forward it to the spawned process, which may set
+  `Process.put(:"$callers", callers)` during its initialization. This may be
+  useful in projects who track process ownership during tests. You can learn
+  more about these keys in [the `Task` module](`Task#module-ancestor-and-caller-tracking`).
   """
   @doc since: "1.5.0"
   @spec start_supervised(Supervisor.child_spec() | module | {module, term}, keyword) ::