lib-lua: Extend lib-lua C-API documentation

Author: vmo69

docs/core/admin/lua/lib_lua.md

@@ -49,15 +49,25 @@ When script is being unloaded, `script_deinit()` function is called, if found.
 
 ## C API
 
+### `struct event *dlua_check_event(lua_State *L, int arg)`
+
+Check the argument with index `arg` from stack and try to convert
+it to an Dovecot Event. Throws an error of the argument is no valid
+Dovecot Event.
+
 ### `void dlua_dovecot_register(struct dlua_script *script)`
 
 Register dovecot variable. This item can also be extended by context specific
 tables, like authentication database adds `dovecot.auth`.
 
-### `void dlua_push_event(struct event *event)`
+### `void dlua_push_event(lua_State *L, struct event *event)`
 
 Pushes an Dovecot Event to stack.
 
+### `void dlua_push_timeval(lua_State *L, const struct timeval *tv)`
+
+Pushes an timeval struct to stack as integer.
+
 ## Lua API
 
 ### Base Functions