docs(eval): add parameter type for vim.fn.mode() (#26776)

runtime/lua/vim/_meta/vimfn.lua

@@ -5829,8 +5829,9 @@ function vim.fn.mkdir(name, flags, prot) end
 --- the leading character(s).
 --- Also see |visualmode()|.
 ---
+--- @param expr? any
 --- @return any
-function vim.fn.mode() end
+function vim.fn.mode(expr) end
 
 --- Convert a list of Vimscript objects to msgpack. Returned value is a
 --- |readfile()|-style list. When {type} contains "B", a |Blob| is

src/nvim/eval.lua

@@ -7057,7 +7057,7 @@ M.funcs = {
 
     ]=],
     name = 'mode',
-    params = {},
+    params = { { 'expr', 'any' } },
     signature = 'mode([expr])',
   },
   msgpackdump = {