Fix usage of :option: in the docs (#9312).

:option: is used to create a link to an option of python, not to mark
up any instance of any arbitrary command-line option.  These were
changed to ````.

For modules which do have a command-line interface, lists of options
have been properly marked up with the program/cmdoption directives
combo.  Options defined in such blocks can be linked to with :option:
later in the same file, they won’t link to an option of python.

Finally, the markup of command-line fragments in optparse.rst has
been cleaned to use ``x`` instead of ``"x"``, keeping that latter
form for actual Python strings.

Patch by Eli Bendersky and Éric Araujo.
diff --git a/Doc/library/timeit.rst b/Doc/library/timeit.rst
index 89ea7b0..4a0b9c2 100644
--- a/Doc/library/timeit.rst
+++ b/Doc/library/timeit.rst
@@ -117,27 +117,36 @@
 
    python -m timeit [-n N] [-r N] [-s S] [-t] [-c] [-h] [statement ...]
 
-where the following options are understood:
+Where the following options are understood:
 
--n N/:option:`--number=N`
+.. program:: timeit
+
+.. cmdoption:: -n N, --number=N
+
    how many times to execute 'statement'
 
--r N/:option:`--repeat=N`
+.. cmdoption:: -r N, --repeat=N
+
    how many times to repeat the timer (default 3)
 
--s S/:option:`--setup=S`
-   statement to be executed once initially (default ``'pass'``)
+.. cmdoption:: -s S, --setup=S
 
--t/:option:`--time`
+   statement to be executed once initially (default ``pass``)
+
+.. cmdoption:: -t, --time
+
    use :func:`time.time` (default on all platforms but Windows)
 
--c/:option:`--clock`
+.. cmdoption:: -c, --clock
+
    use :func:`time.clock` (default on Windows)
 
--v/:option:`--verbose`
+.. cmdoption:: -v, --verbose
+
    print raw timing results; repeat for more digits precision
 
--h/:option:`--help`
+.. cmdoption:: -h, --help
+
    print a short usage message and exit
 
 A multi-line statement may be given by specifying each line as a separate