Use connect_to_raillike for rail

Used value: 2

game_api.txt

@@ -194,6 +194,22 @@ xpanes.register_pane(subname, def)
 	^ Recipe field only
 }
 
+Raillike definitions
+--------------------
+The following nodes use the group `connect_to_raillike` and will only connect to
+raillike nodes within this group and the same group value.
+Use `minetest.raillike_group(<Name>)` to get the group value.
+
+| Node type		| Raillike group name
++-----------------------+----------------------------------
+| default:rail		| "rail"
+
+Example:
+If you want to add a new rail type and want it to connect with default:rail,
+add `connect_to_raillike=minetest.raillike_group("rail")` into the `groups` table
+of your node.
+
+
 Default sounds
 --------------
 Sounds inside the default table can be used within the sounds field of node definitions.