Marked keystrokes with the :kbd: role.

Fixed the case of the "Ctrl-" prefixes.

diff --cc Doc/library/asyncio-eventloop.rst
Simple merge

diff --cc Doc/library/asyncio-protocol.rst
Simple merge

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

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

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

diff --cc Doc/tutorial/appendix.rst
Simple merge

diff --cc Doc/tutorial/interpreter.rst
Simple merge

diff --cc Doc/using/cmdline.rst
Simple merge

diff --cc Lib/test/test_os.py
Simple merge

diff --cc Lib/unittest/main.py
Simple merge