vim: f and t multiline option (#8448)

I'm not sure how compliant you're aiming to be with vim, but the `f`
behavior is more useful when it can search on multiple lines instead of
a single one, so I'd like to propose this change.

This change is quite frequent in vim/neovim as a plugin (e.g.
[clever-f](https://github.com/VSCodeVim/Vim),
[improved-ft](https://github.com/backdround/improved-ft.nvim), etc), and
in other vim emulations (e.g.
[vscode-vim](https://github.com/VSCodeVim/Vim)).

docs/src/configuring_zed__configuring_vim.md

@@ -144,6 +144,23 @@ Currently supported vim-specific commands (as of Zed 0.106):
     to sort the current selection (with i, case-insensitively)
 ```
 
+## Vim settings
+
+Some vim settings are available to modify the default vim behavior:
+
+```json
+{
+  "vim": {
+    // "always": use system clipboard
+    // "never": don't use system clipboard
+    // "on_yank": use system clipboard for yank operations
+    "use_system_clipboard": "always",
+    // Enable multi-line find for `f` and `t` motions
+    "use_multiline_find": false
+  }
+}
+```
+
 ## Related settings
 
 There are a few Zed settings that you may also enjoy if you use vim mode: