Remove duplicate kill-window documentation

In this anchor: https://tmuxp.readthedocs.io/en/latest/about_tmux.html#kill-window
`kill-window` is defined twice.

Author: jstoja

doc/about_tmux.rst

@@ -449,15 +449,14 @@ Kill window
 
 .. code-block:: bash
 
-    $ tmux kill-window
+    $ tmux kill-window [-t target-window]
 
 ===================   ====================================================
 Short cut             Action
 -------------------   ----------------------------------------------------
 ``&``                 Kill the current window.
 ===================   ====================================================
 
-
 Kill pane
 ---------
 
@@ -471,19 +470,6 @@ Short cut             Action
 ``x``                 Kill the current pane.
 ===================   ====================================================
 
-Kill window
------------
-
-.. code-block:: bash
-
-    $ tmux kill-window [-t target-window]
-
-===================   ====================================================
-Short cut             Action
--------------------   ----------------------------------------------------
-``&``                 Kill the current window.
-===================   ====================================================
-
 Splitting windows into panes
 ----------------------------