Docs: add f_generator attribute to datamodel page and update index

Author: Devansh-b

Doc/reference/datamodel.rst

@@ -1633,6 +1633,7 @@ and are also passed to registered trace functions.
 
 .. index::
    single: f_back (frame attribute)
+   single: f_generator (frame attribute)
    single: f_code (frame attribute)
    single: f_globals (frame attribute)
    single: f_locals (frame attribute)
@@ -1648,6 +1649,10 @@ Special read-only attributes
      - Points to the previous stack frame (towards the caller),
        or ``None`` if this is the bottom stack frame
 
+   * - .. attribute:: frame.f_generator
+     - Returns the generator or coroutine object that owns this frame,
+       or ``None`` if the frame is of a regular function.
+
    * - .. attribute:: frame.f_code
      - The :ref:`code object <code-objects>` being executed in this frame.
        Accessing this attribute raises an :ref:`auditing event <auditing>`