fix(startup)!: "nvim -l" message does not end with newline #24215

Close #24180

runtime/doc/news.txt

@@ -38,6 +38,9 @@ The following changes may require adaptations in user config or plugins.
 • When switching windows, |CursorMoved| autocommands trigger when Nvim is back
   in the main loop rather than immediately. This is more compatible with Vim.
 
+• |-l| ensures output ends with a newline if the script prints messages and
+  doesn't cause Nvim to exit.
+
 • |LspRequest| and LspProgressUpdate (renamed to |LspProgress|) autocmds were
   promoted from a |User| autocmd to first class citizen.
 

runtime/doc/starting.txt

@@ -227,6 +227,8 @@ argument.
 		
 		Sets 'verbose' to 1 (like "-V1"), so Lua `print()` writes to
 		output.
+		If {script} prints messages and doesn't cause Nvim to exit,
+		Nvim ensures output ends with a newline.
 
 		Arguments before "-l" are processed before executing {script}.
 		This example quits before executing "foo.lua": >