docs(gen): support language annotation in docstrings

src/nvim/api/win_config.c

@@ -55,13 +55,13 @@
 /// this should not be used to specify arbitrary WM screen positions.
 ///
 /// Example (Lua): window-relative float
-/// <pre>
+/// <pre>lua
 ///     vim.api.nvim_open_win(0, false,
 ///       {relative='win', row=3, col=3, width=12, height=3})
 /// </pre>
 ///
 /// Example (Lua): buffer-relative float (travels as buffer is scrolled)
-/// <pre>
+/// <pre>lua
 ///     vim.api.nvim_open_win(0, false,
 ///       {relative='win', width=12, height=3, bufpos={100,10}})
 /// </pre>