Add Lua bitop library (#9847)

doc/lua_api.txt

@@ -8825,3 +8825,10 @@ Used by `minetest.register_authentication_handler`.
         -- Returns an iterator (use with `for` loops) for all player names
         -- currently in the auth database
     }
+
+Bit Library
+-----------
+
+Functions: bit.tobit, bit.tohex, bit.bnot, bit.band, bit.bor, bit.bxor, bit.lshift, bit.rshift, bit.arshift, bit.rol, bit.ror, bit.bswap
+
+See http://bitop.luajit.org/ for advanced information.