pythongh-91533: Move much of typing.rst to a new 'Guide to typing features' document

Author: AlexWaygood

Doc/howto/index.rst

@@ -24,6 +24,7 @@ Currently, the HOWTOs are:
    regex.rst
    sockets.rst
    sorting.rst
+   typing.rst
    unicode.rst
    urllib2.rst
    argparse.rst