Updated missing periods in cmdline.rst (GH-17173)

(cherry picked from commit 0fe0b88)

Co-authored-by: Jules Lasne (jlasne) <jules.lasne@gmail.com>

Doc/using/cmdline.rst

@@ -454,7 +454,7 @@ Miscellaneous options
        on a crash.
      * Enable :ref:`asyncio debug mode <asyncio-debug-mode>`.
      * Set the :attr:`~sys.flags.dev_mode` attribute of :attr:`sys.flags` to
-       ``True``
+       ``True``.
      * :class:`io.IOBase` destructor logs ``close()`` exceptions.
 
    * ``-X utf8`` enables UTF-8 mode for operating system interfaces, overriding
@@ -773,8 +773,8 @@ conflict.
 
    * ``debug``: install debug hooks on top of the :ref:`default memory
      allocators <default-memory-allocators>`.
-   * ``malloc_debug``: same as ``malloc`` but also install debug hooks
-   * ``pymalloc_debug``: same as ``pymalloc`` but also install debug hooks
+   * ``malloc_debug``: same as ``malloc`` but also install debug hooks.
+   * ``pymalloc_debug``: same as ``pymalloc`` but also install debug hooks.
 
    See the :ref:`default memory allocators <default-memory-allocators>` and the
    :c:func:`PyMem_SetupDebugHooks` function (install debug hooks on Python