DOC: Add links to the __class_getitem__ docs

Author: BvB93

doc/source/reference/arrays.dtypes.rst

@@ -562,3 +562,10 @@ The following methods implement the pickle protocol:
 
    dtype.__reduce__
    dtype.__setstate__
+
+Utility method for typing:
+
+.. autosummary::
+   :toctree: generated/
+
+   dtype.__class_getitem__

doc/source/reference/arrays.ndarray.rst

@@ -621,3 +621,10 @@ String representations:
 
    ndarray.__str__
    ndarray.__repr__
+
+Utility method for typing:
+
+.. autosummary::
+   :toctree: generated/
+
+   ndarray.__class_getitem__

doc/source/reference/arrays.scalars.rst

@@ -196,10 +196,10 @@ Inexact types
    ``f16`` prints as ``0.1`` because it is as close to that value as possible,
    whereas the other types do not as they have more precision and therefore have
    closer values.
-   
+
    Conversely, floating-point scalars of different precisions which approximate
    the same decimal value may compare unequal despite printing identically:
-   
+
        >>> f16 = np.float16("0.1")
        >>> f32 = np.float32("0.1")
        >>> f64 = np.float64("0.1")
@@ -498,6 +498,13 @@ The exceptions to the above rules are given below:
    generic.__setstate__
    generic.setflags
 
+Utility method for typing:
+
+.. autosummary::
+   :toctree: generated/
+
+   number.__class_getitem__
+
 
 Defining new types
 ==================