Add the game

mods/xcompat/doc/functions.md

@@ -0,0 +1,16 @@
+# Functions API
+
+## `can_interact_with_node(player, pos)`
+
+returns `bool`
+
+checks for the ability to interact with a node via:
+
+* if a player
+* owner metadata key
+* `protection_bypass`
+
+supports
+
+* minetest game default if present
+* else polyfill