docs(configuration): describe new utility "atuin-bind" for Bash

Author: akinomyoga

src/content/docs/configuration/key-binding.mdx

@@ -90,28 +90,55 @@ used in combination with the config
 
 ## bash
 
-Atuin provides a bindable shell function "`__atuin_history`" for keybindings in
-Bash.  The flag `--shell-up-key-binding` can be optionally specified to the
-first argument for keybindings to the <kbd>up</kbd> key or similar keys.
+Atuin (`>= 18.10.0`) provides a shell function `atuin-bind` to set up
+keybindings easily:
+
+```
+atuin-bind [-m KEYMAP] KEYSEQ COMMAND
+```
+
+`KEYMAP` is one of `emacs`, `vi-insert`, and `vi-command` and specifies the
+target keymap where the keybinding is defined.  `KEYSEQ` specifies a key
+sequence in the format used in `bind '"KEYSEQ": ...'`.  `COMMAND` specifies a
+shell command to run with the keybindings.  The following special commands can
+be used as well as an arbitrary shell command:
+
+| Command                 | Description                                                                         |
+| ----------------------- | ----------------------------------------------------------------------------------- |
+| `atuin-search`          | Standard search                                                                     |
+| `atuin-search-emacs`    | Standard search with the `emacs` keymap mode                                        |
+| `atuin-search-viins`    | Standard search with the `vim-insert` keymap mode                                   |
+| `atuin-search-vicmd`    | Standard search with the `vim-insert` keymap mode                                   |
+| `atuin-up-search`       | Search command for <kbd>up</kbd> or similar keys                                    |
+| `atuin-up-search-emacs` | Search command for <kbd>up</kbd> or similar keys, with the `emacs` keymap mode      |
+| `atuin-up-search-viins` | Search command for <kbd>up</kbd> or similar keys, with the `vim-insert` keymap mode |
+| `atuin-up-search-vicmd` | Search command for <kbd>up</kbd> or similar keys, with the `vim-insert` keymap mode |
+
+The keymap mode controls the initial keymap in the Atuin search and is
+determined in combination with the config
+["keymap\_mode"](https://docs.atuin.sh/configuration/config/#keymap_mode)
+(`atuin >= 18.0`).
+
 
 ```
 export ATUIN_NOBIND="true"
 eval "$(atuin init bash)"
 
 # bind to ctrl-r, add any other bindings you want here too
-bind -x '"\C-r": __atuin_history'
+atuin-bind '\C-r' atuin-search
 
 # bind to the up key, which depends on terminal mode
-bind -x '"\e[A": __atuin_history --shell-up-key-binding'
-bind -x '"\eOA": __atuin_history --shell-up-key-binding'
+atuin-bind '\e[A' atuin-up-search
+atuin-bind '\eOA' atuin-up-search
 ```
 
-For the keybindings in the `vi` editing mode, the options
-`--keymap-mode=vim-insert` and `--keymap-mode=vim-normal` (`atuin >= 18.0`) can
-be additionally specified to the shell function `__atuin_history` in
-combination with the config
-["keymap\_mode"](https://docs.atuin.sh/configuration/config/#keymap_mode)
-(`atuin >= 18.0`) to start the Atuin search in respective keymap modes.
+With older versions of Atuin, the user needs to bind a bindable shell function
+"`__atuin_history`" directly using Bash's `bind`.  The flag
+`--shell-up-key-binding` can be optionally specified to the first argument for
+keybindings to the <kbd>up</kbd> key or similar keys.  For the keybindings in
+the `vi` editing mode, the options `--keymap-mode=vim-insert` and the keymap
+mode `--keymap-mode=vim-normal` (`atuin >= 18.0`) can be additionally specified
+to the shell function `__atuin_history`.
 
 ## fish
 Edit key bindings in FISH shell by adding the following to ~/.config/fish/config.fish

src/content/docs/guide/installation.mdx

@@ -163,8 +163,9 @@ After installing, remember to restart your shell.
                     While Atuin will ignore commands prefixed with whitespace, they may still end up in your bash history.
                     Please check your configuration! All other shells do not have this issue.
 
-                    To use Atuin in `bash < 4` with bash-preexec, the option `enter_accept` needs
-                    to be turned on (which is so by default).
+                    To use `atuin < 18.10.0` in `bash < 4` with bash-preexec, the option
+                    `enter_accept` needs to be turned on (which is so by default).  There is no
+                    restriction in the latest version of Atuin (>= 18.10.0).
 
                     bash-preexec cannot properly invoke the `preexec` hook for subshell commands
                     `(...)`, function definitions `func() { ...; }`, empty for-in-statements `for