Added "register_hook_proc_spec" script function

Updated documents to address the new function.

artifacts/scripting/hookscripts.txt

@@ -46,6 +46,9 @@ Used from a normal global script if you want to run it at the same point a full
 > void register_hook_proc(int hook, procedure proc)
 The same as register_hook, except that you specifically define which procedure in the current script should be called as a hook (instead of "start" by default). Pass procedure the same as how you use dialog option functions. This IS the recommended way to use hook scripts, as it gives both modularity (each mod logic in a separate global script, no conflicts if you don't use "hs_*.int" scripts) and flexibility (you can place all related hook scripts for specific mod in a single script!).
 
+> void register_hook_proc_spec(int hook, procedure proc)
+Works very similar to register_hook_proc, except that it registers the current script at the end of the hook script execution chain (i.e. the script will be executed after all previously registered scripts for the same hook, including the hs_*.int script.) All scripts hooked to a single hook point with this function are executed in exact order of how they were registered, as opposed to the description below, which refers to using register_hook/register_hook_proc functions.
+
 NOTE: you can hook several scripts to a single hook point, for example if it's different mods from different authors or just some different aspects of one larger mod. In this case scripts are executed in reverse order of how they were registered. When one of the scripts in a chain returns value with "set_sfall_return", the next script may override this value if calls "set_sfall_return" again. Sometimes you need to multiply certain value in a chain of hook scripts.
 Example: let's say we have a Mod A which reduces all "to hit" chances by 50%. The code might look like this: