DOC: Add missing doc Index.array and Index.to_numpy (pandas-dev#57353)

Author: luke396

doc/source/reference/indexing.rst

@@ -41,6 +41,7 @@ Properties
    Index.empty
    Index.T
    Index.memory_usage
+   Index.array
 
 Modifying and computations
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -103,6 +104,7 @@ Conversion
    Index.to_list
    Index.to_series
    Index.to_frame
+   Index.to_numpy
    Index.view
 
 Sorting