IVGCVSW-6946 Add Pool3D to tflite delegate

 * Add new test and test helper for Pool3d
 * Add new custom operator to switch in armnn_delegate.cpp
 * Add new pool3d function to pooling.hpp
 * Update doxygen

Signed-off-by: Ryan OShea <ryan.oshea3@arm.com>
Change-Id: I77a541bf423b337c749e70c564cdd727efe2fd05
diff --git a/docs/05_03_delegate.dox b/docs/05_03_delegate.dox
index 625b253..d1c41fe 100644
--- a/docs/05_03_delegate.dox
+++ b/docs/05_03_delegate.dox
@@ -43,6 +43,8 @@
 
 - AVERAGE_POOL_2D, Supported Fused Activation: RELU , RELU6 , TANH, NONE
 
+- AVERAGE_POOL_3D
+
 - BATCH_TO_SPACE_ND
 
 - CAST
@@ -107,6 +109,8 @@
 
 - MAX_POOL_2D, Supported Fused Activation: RELU , RELU6 , TANH, NONE
 
+- MAX_POOL_3D
+
 - MEAN
 
 - MINIMUM