org.el: New speed command "k" to kill the subtree at point

* lisp/org.el (org-speed-commands-default): Add "k" to kill
the subtree at point.

etc/ORG-NEWS

@@ -387,6 +387,7 @@ Set option ~org-src-window-setup~ to ~split-window-below~.
 When sorting alphabetically, ~org-sort-entries~ and
 ~org-tags-sort-function~ now sort according to the locale’s collation
 rules instead of by code-point.
+*** New speed command "k" to kill (cut) the subtree at point
 * Version 9.1
 
 ** Incompatible changes

lisp/org.el

@@ -19095,6 +19095,7 @@ COMMANDS is a list of alternating OLDDEF NEWDEF command names."
     ("C" . org-shifttab)
     (" " . org-display-outline-path)
     ("s" . org-narrow-to-subtree)
+    ("k" . org-cut-subtree)
     ("=" . org-columns)
     ("Outline Structure Editing")
     ("U" . org-metaup)