Restore Cosmo-added comment.

third_party/lua/lauxlib.c

@@ -38,10 +38,35 @@
 __static_yoink("lua_notice");
 
 
-/*
-** This file uses only the official API of Lua.
-** Any function declared here could be written as an application function.
- */
+/**
+  * @fileoverview The Auxiliary Library
+  *
+  * The auxiliary library provides several convenient functions to interface C
+  * with Lua. While the basic API provides the primitive functions for all
+  * interactions between C and Lua, the auxiliary library provides
+  * higher-level functions for some common tasks.
+  *
+  * All functions and types from the auxiliary library are defined in header
+  * file lauxlib.h and have a prefix luaL_.
+  *
+  * All functions in the auxiliary library are built on top of the basic API,
+  * and so they provide nothing that cannot be done with that API.
+  * Nevertheless, the use of the auxiliary library ensures more consistency to
+  * your code.
+  *
+  * Several functions in the auxiliary library use internally some extra stack
+  * slots. When a function in the auxiliary library uses less than five slots,
+  * it does not check the stack size; it simply assumes that there are enough
+  * slots.
+  *
+  * Several functions in the auxiliary library are used to check C function
+  * arguments. Because the error message is formatted for arguments (e.g.,
+  * "bad argument #1"), you should not use these functions for other stack
+  * values.
+  *
+  * Functions called luaL_check* always raise an error if the check is not
+  * satisfied.
+  */
 
 
 #if !defined(MAX_SIZET)