Clarify the doc for Task.yield

Author: alco

lib/elixir/lib/task.ex

@@ -364,20 +364,21 @@ defmodule Task do
  end
 
  @doc """
- Yields for a task reply in the given time interval.
+ Temporarily blocks the current process waiting for a task reply.
 
- Returns `{:ok, reply}` if the reply is received, `{:exit, reason}`
- if the task exited or `nil` if no reply arrived.
+ Returns `{:ok, reply}` if the reply is received, `nil` if
+ no reply has arrived, or `{:exit, reason}` if the task exited.
+ Keep in mind that normally this function will exit if the task
+ process terminates abnormally. `{:exit, reason}` can only be
+ returned if the task process exited with the reason `:normal`
+ or if it isn't linked to the caller.
 
  A timeout, in milliseconds, can be given with default value
  of `5000`. If the time runs out before a message from
  the task is received, this function will return `nil`
  and the monitor will remain active. Therefore `yield/2` can be
  called multiple times on the same task.
 
- In case the task process dies, this function will exit with the
- same reason as the task.
-
  This function assumes the task's monitor is still active or the
  monitor's `:DOWN` message is in the message queue. If it has been
  demonitored or the message already received, this function will wait