L2SS-883: Extend attribute_wrapper to support >2D arrays

Closes L2SS-883

tangostationcontrol/docs/source/devices/recv.rst

@@ -9,9 +9,11 @@ The ``recv == DeviceProxy("STAT/RECV/1")`` device controls the RCUs, the LBA ant
 
 :Ant_mask_RW: Controls which antennas will actually be configured when attributes referring to antennas are written.
 
-  :type: ``bool[N_RCUs][N_antennas_per_RCU]``
+  :type: ``bool[N_antennas]``
 
-Typically, ``N_RCUs == 32``, and ``N_antennas_per_RCU == 3``.
+Typically, ``N_RCUs == 32``, and ``N_antennas == 96``.
+
+.. note:: The antennas are hooked up to the RCUs in sets of 3, in order.
 
 Error information
 ---------------------
@@ -24,7 +26,7 @@ These attributes summarise the basic state of the device. Any elements which are
 
 :ANT_error_R: Whether the antennas appear usable.
 
-  :type: ``bool[N_RCUs][N_antennas_per_RCU]``
+  :type: ``bool[N_antennas]``
 
 :RCU_IOUT_error_R: Whether there are alarms on any of the amplitudes in the measured currents.