Address return value type for single-element access (#125)

Author: kgryte

spec/API_specification/array_object.md

@@ -558,7 +558,23 @@ Element-wise results must equal the results returned by the equivalent element-w
 (method-__getitem__)=
 ### \_\_getitem\_\_(x, key, /)
 
-_TODO: dependent on the indexing specification._
+Returns `x[key]`.
+
+#### Parameters
+
+-   **x**: _<array;>_
+
+    -   array instance.
+
+-   **key**: _Union\[ int, slice, Tuple\[ Union\[ int, slice ], ... ], <array> ]_
+
+    -   index key.
+
+#### Returns
+
+-   **out**: _<array>_
+
+    -   an array containing the accessed value(s). The returned array must have the same data type as `x`.
 
 (method-__gt__)=
 ### \_\_gt\_\_(x1, x2, /)

spec/API_specification/indexing.md

@@ -151,8 +151,6 @@ Multi-dimensional arrays must extend the concept of single-axis indexing to mult
 
 -   Providing [ellipsis](https://docs.python.org/3/library/constants.html#Ellipsis) must apply `:` to each dimension necessary to index all dimensions (e.g., if `A` has rank `4`, `A[1:, ..., 2:5] == A[1:, :, :, 2:5]`). Only a single ellipsis must be allowed. An `IndexError` exception must be raised if more than one ellipsis is provided.
 
--   The result of multi-axis indexing must be an array of the same data type as the indexed array.
-
 ```{note}
 
 This specification leaves unspecified the behavior of providing a slice which attempts to select elements along a particular axis, but whose starting index is out-of-bounds.
@@ -179,4 +177,11 @@ An array must support indexing via a **single** `M`-dimensional boolean array `B
 
 -   A zero-dimensional boolean index array (equivalent to `True` or `False`) must follow the same axis replacement rules stated above. Namely, a zero-dimensional boolean index array removes zero dimensions and adds a single dimension of length `1` if the index array's value is `True` and of length `0` if the index array's value is `False`. Accordingly, for a zero-dimensional boolean index array `B`, the result of `A[B]` has shape `S = (1, s1, ..., sN)` if the index array's value is `True` and has shape `S = (0, s1, ..., sN)` if the index array's value is `False`.
 
--   The result of indexing into an array via a boolean index array must be an array of the same data type as the indexed array.
+## Return Values
+
+The result of an indexing operation (e.g., multi-axis indexing, boolean array indexing, etc) must be an array of the same data type as the indexed array.
+
+```{note}
+
+The specified return value behavior includes indexing operations which return a single value (e.g., accessing a single element within a one-dimensional array).
+```