Document ctrl-backspace and bind ctrl-delete as well

This has a slightly different behavior than what the CUA user expects:
it fails to eat up trailing spaces.  We should probably fix this.

CHANGELOG.rst

@@ -178,6 +178,7 @@ New or improved bindings
 - The following keys have refined behavior if the terminal supports `disambiguating them <https://sw.kovidgoyal.net/kitty/keyboard-protocol/>`_:
   - :kbd:`shift-enter` now inserts a newline instead of executing the command line.
   - :kbd:`ctrl-backspace` now deletes the last word instead of only one character.
+  - :kbd:`ctrl-delete` deletes the next word (same as :kbd:`alt-d`).
 - New special input functions ``forward-char-passive`` and ``backward-char-passive`` are like their non-passive variants but do not accept autosuggestions or move focus in the completion pager (:issue:`10398`).
 - Vi mode has seen some improvements but continues to suffer from the lack of people working on it.
   - Insert-mode :kbd:`ctrl-n` accepts autosuggestions (:issue:`10339`).

doc_src/interactive.rst

@@ -325,7 +325,7 @@ Some bindings are common across Emacs and vi mode, because they aren't text edit
 
 - :kbd:`ctrl-x` copies the current buffer to the system's clipboard, :kbd:`ctrl-v` inserts the clipboard contents. (see :doc:`fish_clipboard_copy <cmds/fish_clipboard_copy>` and :doc:`fish_clipboard_paste <cmds/fish_clipboard_paste>`)
 
-- :kbd:`alt-d` moves the next word to the :ref:`killring`.
+- :kbd:`alt-d` or :kbd:`ctrl-delete` moves the next word to the :ref:`killring`.
 
 - :kbd:`alt-h` (or :kbd:`f1`) shows the manual page for the current command, if one exists.
 
@@ -362,7 +362,7 @@ To enable emacs mode, use :doc:`fish_default_key_bindings <cmds/fish_default_key
 
 - :kbd:`delete` or :kbd:`backspace` removes one character forwards or backwards respectively. This also goes for :kbd:`ctrl-h`, which is indistinguishable from backspace.
 
-- :kbd:`alt-backspace` removes one word backwards.
+- :kbd:`alt-backspace` removes one word backwards. If supported by the terminal, :kbd:`ctrl-backspace` does the same.
 
 - :kbd:`alt-<` moves to the beginning of the commandline, :kbd:`alt->` moves to the end.
 

share/functions/fish_default_key_bindings.fish

@@ -76,6 +76,7 @@ function fish_default_key_bindings -d "emacs-like key binds"
     bind --preset $argv alt-c capitalize-word
     bind --preset $argv alt-backspace backward-kill-word
     bind --preset $argv ctrl-backspace backward-kill-word
+    bind --preset $argv ctrl-delete kill-word
     bind --preset $argv alt-b backward-word
     bind --preset $argv alt-f forward-word
     if test "$TERM_PROGRAM" = Apple_Terminal