Issue #12602: Add missing cross-references to runpy and using/cmdline docs.

Patch by Éric Araujo.

Doc/library/runpy.rst

@@ -75,6 +75,9 @@ The :mod:`runpy` module provides two functions:
    arguments. It is recommended that the :mod:`sys` module be left alone when
    invoking this function from threaded code.
 
+   .. seealso::
+      The :option:`-m` option offering equivalent functionality from the
+      command line.
 
    .. versionchanged:: 3.1
       Added ability to execute packages by looking for a ``__main__`` submodule.
@@ -146,6 +149,10 @@ The :mod:`runpy` module provides two functions:
    limitations still apply, use of this function in threaded code should be
    either serialised with the import lock or delegated to a separate process.
 
+   .. seealso::
+      :ref:`using-on-interface-options` for equivalent functionality on the
+      command line (``python path/to/script``).
+
    .. versionadded:: 3.2
 
    .. versionchanged:: 3.4
@@ -156,13 +163,13 @@ The :mod:`runpy` module provides two functions:
 
 .. seealso::
 
-   :pep:`338` - Executing modules as scripts
+   :pep:`338` -- Executing modules as scripts
       PEP written and implemented by Nick Coghlan.
 
-   :pep:`366` - Main module explicit relative imports
+   :pep:`366` -- Main module explicit relative imports
       PEP written and implemented by Nick Coghlan.
 
-   :pep:`451` - A ModuleSpec Type for the Import System
+   :pep:`451` -- A ModuleSpec Type for the Import System
       PEP written and implemented by Eric Snow
 
    :ref:`using-on-general` - CPython command line details

Doc/tutorial/interpreter.rst

@@ -63,6 +63,8 @@ When a script file is used, it is sometimes useful to be able to run the script
 and enter interactive mode afterwards.  This can be done by passing :option:`-i`
 before the script.
 
+All command line options are described in :ref:`using-on-general`.
+
 
 .. _tut-argpassing:
 

Doc/using/cmdline.rst

-.. highlightlang:: none
+.. highlightlang:: sh
 
 .. ATTENTION: You probably should update Misc/python.man, too, if you modify
-.. this file.
+   this file.
 
 .. _using-on-general:
 
@@ -148,6 +148,10 @@ source.
    added to the start of :data:`sys.path` and the ``__main__.py`` file in
    that location is executed as the :mod:`__main__` module.
 
+   .. seealso::
+      :func:`runpy.run_path`
+         Equivalent functionality directly available to Python code
+
 
 If no interface option is given, :option:`-i` is implied, ``sys.argv[0]`` is
 an empty string (``""``) and the current directory will be added to the
@@ -155,11 +159,11 @@ start of :data:`sys.path`.  Also, tab-completion and history editing is
 automatically enabled, if available on your platform (see
 :ref:`rlcompleter-config`).
 
+.. seealso::  :ref:`tut-invoking`
+
 .. versionchanged:: 3.4
    Automatic enabling of tab-completion and history editing.
 
-.. seealso::  :ref:`tut-invoking`
-
 
 Generic options
 ~~~~~~~~~~~~~~~