docs: add window_picker.picker documentation

Author: davidsierradz

doc/nvim-tree-lua.txt

@@ -348,6 +348,7 @@ Subsequent calls to setup will replace the previous configuration.
           resize_window = true,
           window_picker = {
             enable = true,
+            picker = "default",
             chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890",
             exclude = {
               filetype = { "notify", "packer", "qf", "diff", "fugitive", "fugitiveblame" },
@@ -999,6 +1000,18 @@ Configuration for various actions.
             from which you last opened the tree.
               Type: `boolean`, Default: `true`
 
+            *nvim-tree.actions.open_file.window_picker.picker*
+            Change the default window picker, can be a string `default` or a function.
+            The function should return the window id that will open the node,
+            or `nil` if an invalid window is picked or user cancelled the action.
+              Type: `string or function`, Default: `"default"`
+              Using s1n7ax/nvim-window-picker plugin:
+              e.g. >
+                require('window-picker').setup()
+                function()
+                  return require('window-picker').pick_window()
+                end
+<
             *nvim-tree.actions.open_file.window_picker.chars*
             A string of chars used as identifiers by the window picker.
               Type: `string`, Default: `"ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"`