feat : added PadBorderType::Zero & added documentation to known padding types

include/aidge/operator/Pad.hpp

@@ -26,7 +26,19 @@
 
 namespace Aidge {
 enum class PadAttr { BeginEndBorders, BorderType, BorderValue };
-enum class PadBorderType { Constant, Edge, Reflect, Wrap };
+enum class PadBorderType { 
+    /** @brief all out of bound values will be set to a given value.*/
+    Constant,
+    Edge, 
+    Reflect, 
+    Wrap, 
+    /** @brief all out of bound values will take the value 
+     *of their nearest neighbour
+     */
+    Nearest,
+    /** @brief all out of bound values will be set to 0.*/
+    Zero,
+};
 
 template <DimIdx_t DIM>
 class Pad_Op : public OperatorTensor,