vim-patch:d7d6a6f: runtime(doc): Improve doc for cmdline-autocompletion

- Address https://github.com/vim/vim/pull/18219#issuecomment-3264634710
- Make the cmdline-autocompletion help more user friendly

closes: vim/vim#18245

d7d6a6f05a

Co-authored-by: Girish Palya <girishji@gmail.com>

src/nvim/eval.lua

@@ -13092,7 +13092,6 @@ M.funcs = {
     desc = [==[
       Start wildcard expansion in the command-line, using the
       behavior defined by the 'wildmode' and 'wildoptions' settings.
-      See |cmdline-completion|.
 
       This function also enables completion in search patterns such
       as |/|, |?|, |:s|, |:g|, |:v| and |:vimgrep|.
@@ -13100,22 +13099,15 @@ M.funcs = {
       Unlike pressing 'wildchar' manually, this function does not
       produce a beep when no matches are found and generally
       operates more quietly.  This makes it suitable for triggering
-      completion automatically, such as from an |:autocmd|.
-      				*cmdline-autocompletion*
-      Example: To make the completion menu pop up automatically as
-      you type on the command line, use: >vim
-      	autocmd CmdlineChanged [:/\?] call wildtrigger()
-      	set wildmode=noselect:lastused,full wildoptions=pum
-      <
-      To retain normal history navigation (up/down keys): >vim
-      	cnoremap <Up>   <C-U><Up>
-      	cnoremap <Down> <C-U><Down>
-      <
-      To set an option specifically when performing a search, e.g.
-      to set 'pumheight': >vim
-      	autocmd CmdlineEnter [/\?] set pumheight=8
-      	autocmd CmdlineLeave [/\?] set pumheight&
-      <
+      completion automatically.
+
+      Note: After navigating command-line history, the first call to
+      wildtrigger() is a no-op; a second call is needed to start
+      expansion.  This is to support history navigation in
+      command-line autocompletion.
+
+      See |cmdline-autocompletion|.
+
       Return value is always 0.
     ]==],
     name = 'wildtrigger',