lua_api.txt: Add mod_orgin to node def (#10697)

doc/lua_api.txt

@@ -7612,6 +7612,13 @@ Used by `minetest.register_node`.
         -- intensity: 1.0 = mid range of regular TNT.
         -- If defined, called when an explosion touches the node, instead of
         -- removing the node.
+        
+        mod_origin = "modname",
+        -- stores which mod actually registered a node
+        -- if it can not find a source, returns "??"
+        -- useful for getting what mod truly registered something
+        -- example: if a node is registered as ":othermodname:nodename", 
+        -- nodename will show "othermodname", but mod_orgin will say "modname"
     }
 
 Crafting recipes