docs: use "ev" convention in event-handlers

Problem:
In autocmd examples, using "args" as the event-object name is vague and
may be confused with a user-command.

Solution:
Use "ev" as the conventional event-object name.

runtime/lua/vim/termcap.lua

@@ -33,8 +33,8 @@ function M.query(caps, cb)
 
   local id = vim.api.nvim_create_autocmd('TermResponse', {
     nested = true,
-    callback = function(args)
-      local resp = args.data.sequence ---@type string
+    callback = function(ev)
+      local resp = ev.data.sequence ---@type string
       local k, rest = resp:match('^\027P1%+r(%x+)(.*)$')
       if k and rest then
         local cap = vim.text.hexdecode(k)