Issue #18757: Improved cross-references in the concurrent package.

diff --cc Doc/library/multiprocessing.rst
index f58c3081a82223ffa14de9fc290d17ce8253d46a,3c9c9aae78581d5da87f5c8ad5536b32f88b80a0..0071025e762feebceadf161a8f9630c0be274f5f
--- 1/Doc/library/multiprocessing.rst
--- 2/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@@ -2476,14 -2394,14 +2485,15 @@@ start method
  
  More picklability
  
 -    Ensure that all arguments to :meth:`Process.__init__` are picklable.  This
 -    means, in particular, that bound or unbound methods cannot be used directly
 -    as the ``target`` argument on Windows --- just define a function and use
 -    that instead.
 +    Ensure that all arguments to :meth:`Process.__init__` are
 +    picklable.  This means, in particular, that bound or unbound
 +    methods cannot be used directly as the ``target`` (unless you use
 +    the *fork* start method) --- just define a function and use that
 +    instead.
  
-     Also, if you subclass :class:`Process` then make sure that instances will be
-     picklable when the :meth:`Process.start` method is called.
+     Also, if you subclass :class:`~multiprocessing.Process` then make sure that
+     instances will be picklable when the :meth:`Process.start
+     <multiprocessing.Process.start>` method is called.
  
  Global variables
  

diff --cc Doc/library/select.rst
Simple merge

diff --cc Doc/library/subprocess.rst
Simple merge