docs: misc #24163

- Also delete old perl scripts which are not used since 8+ years ago.

fix #23251
fix #27367
ref https://github.com/neovim/neovim/issues/2252#issuecomment-1902662577

Helped-by: Daniel Kongsgaard <dakongsgaard@gmail.com>
Co-authored-by: Kevin Pham <keevan.pham@gmail.com>

src/nvim/api/autocmd.c

@@ -381,15 +381,15 @@ cleanup:
 ///             - desc (string) optional: description (for documentation and troubleshooting).
 ///             - callback (function|string) optional: Lua function (or Vimscript function name, if
 ///             string) called when the event(s) is triggered. Lua callback can return a truthy
-///             value (not `false` or `nil`) to delete the autocommand. Receives a table argument
-///             with these keys:
+///             value (not `false` or `nil`) to delete the autocommand. Receives one argument,
+///             a table with these keys: [event-args]()
 ///                 - id: (number) autocommand id
 ///                 - event: (string) name of the triggered event |autocmd-events|
 ///                 - group: (number|nil) autocommand group id, if any
 ///                 - match: (string) expanded value of [<amatch>]
 ///                 - buf: (number) expanded value of [<abuf>]
 ///                 - file: (string) expanded value of [<afile>]
-///                 - data: (any) arbitrary data passed from [nvim_exec_autocmds()]
+///                 - data: (any) arbitrary data passed from [nvim_exec_autocmds()] [event-data]()
 ///             - command (string) optional: Vim command to execute on event. Cannot be used with
 ///             {callback}
 ///             - once (boolean) optional: defaults to false. Run the autocommand

src/nvim/channel.c

@@ -544,10 +544,9 @@ uint64_t channel_from_stdio(bool rpc, CallbackReader on_output, const char **err
   }
 #else
   if (embedded_mode) {
-    // In embedded mode redirect stdout and stdin to stderr, since they are used for the UI channel.
-    // NOTE: fnctl with F_DUPFD_CLOEXEC is used instead of dup to prevent child processes from
-    // inheriting the file descriptors, which make it impossible for UIs to detect when nvim exits
-    // while one or more of its child processes are still running.
+    // Redirect stdout/stdin (the UI channel) to stderr. Use fnctl(F_DUPFD_CLOEXEC) instead of dup()
+    // to prevent child processes from inheriting the file descriptors, which are used by UIs to
+    // detect when Nvim exits.
     stdin_dup_fd = fcntl(STDIN_FILENO, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
     stdout_dup_fd = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, STDERR_FILENO + 1);
     dup2(STDERR_FILENO, STDOUT_FILENO);

src/nvim/options.lua

@@ -9310,6 +9310,7 @@ return {
 
         Level   Messages ~
         ----------------------------------------------------------------------
+        1	Enables Lua tracing (see above). Does not produce messages.
         2	When a file is ":source"'ed, or |shada| file is read or written.
         3	UI info, terminal capabilities.
         4	Shell commands.