feat: rename experimental_watch_for_changes -> watch_for_changes

I've been using this for a while now and haven't seen any issues. We can
take "experimental" out of the name.

lua/oil/config.lua

@@ -50,7 +50,7 @@ local default_config = {
   -- Set to `false` to disable, or "name" to keep it on the file names
   constrain_cursor = "editable",
   -- Set to true to watch the filesystem for changes and reload oil
-  experimental_watch_for_changes = false,
+  watch_for_changes = false,
   -- Keymaps in oil buffer. Can be any value that `vim.keymap.set` accepts OR a table of keymap
   -- options with a `callback` (e.g. { callback = function() ... end, desc = "", mode = "n" })
   -- Additionally, if it is a string that matches "actions.<name>",
@@ -207,6 +207,11 @@ M.setup = function(opts)
     )
   end
 
+  -- This option was renamed because it is no longer experimental
+  if new_conf.experimental_watch_for_changes then
+    new_conf.watch_for_changes = true
+  end
+
   for k, v in pairs(new_conf) do
     M[k] = v
   end