docs: add links to module source

Author: DimmaDont

Doc/library/msvcrt.rst

@@ -7,6 +7,8 @@
 
 .. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
 
+**Source code:** :source:`PC/msvcrtmodule.c`
+
 --------------
 
 These functions provide access to some useful capabilities on Windows platforms.

Doc/library/winreg.rst

@@ -7,6 +7,8 @@
 
 .. sectionauthor:: Mark Hammond <MarkH@ActiveState.com>
 
+**Source code:** :source:`PC/winreg.c`
+
 --------------
 
 These functions expose the Windows registry API to Python.  Instead of using an

Doc/library/winsound.rst

@@ -8,6 +8,8 @@
 .. moduleauthor:: Toby Dickenson <htrd90@zepler.org>
 .. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
 
+**Source code:** :source:`PC/winsound.c`
+
 --------------
 
 The :mod:`winsound` module provides access to the basic sound-playing machinery