Docs: Add Action Slot example code to PyAPI docs

Add some example code for working with Action slots.

Reference: https://projects.blender.org/blender/blender-manual/issues/105297
Pull Request: https://projects.blender.org/blender/blender/pulls/151510

doc/python_api/examples/bpy.types.ActionSlot.1.py

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+"""
+Action Slots organize animation data within an action. Each action has slots with specific animation
+data. An animated data-block specifies an action and a slot, determining the animation data it uses.
+See the `Blender Manual <https://docs.blender.org/manual/en/5.1/animation/actions.html#action-slots>`_
+for how Action Slots are used, or the `technical documentation <https://developer.blender.org/docs/features/animation/>`_
+for details on the animation system's architecture.
+
+Create & Access an Action Slot
+++++++++++++++++++++++++++++++
+To get started with Action Slots, you can easily create them by inserting a keyframe on an object. When you do this,
+Blender automatically creates an Action & Slot for that data-block.
+
+"""
+import bpy
+
+# Assume Suzanne mesh is present in the scene.
+suzanne = bpy.data.objects["Suzanne"]
+
+# Create animation data and an action for Suzanne:
+# Slot will be automatically created.
+suzanne.keyframe_insert("location", index=0)
+
+# Action slots can be accessed like this:
+action = suzanne.animation_data.action
+for slot in action.slots:
+    print(f"Slot Identifier {slot.identifier!r} "
+          f"with name {slot.name_display!r} "
+          f"targets ID type {slot.target_id_type!r}")

doc/python_api/examples/bpy.types.ActionSlot.2.py

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+"""
+Manually Create an Action Slot
+++++++++++++++++++++++++++++++
+If required you can also manually create Action Slots on an Action. Note the ``target_id_type``
+that matches the data-block type. Identifiers start with a prefix based on the ID type,
+e.g. "OB" for objects, followed by the name. There can be identifiers like ``OBSuzanne``
+and ``MESuzanne`` and the name (``Suzanne``) can be shared between them. This is intentional,
+so that the slots and the datablocks can have the same name.
+
+"""
+# Actions creation.
+action = bpy.data.actions.new("SuzanneAction")
+
+# Creation of slots requires an ID type and a name.
+slot = action.slots.new(id_type='OBJECT', name="Suzanne")
+print(f"slot type={slot.target_id_type!r} "
+      f"name={slot.name_display!r} "
+      f"identifier={slot.identifier!r}")
+
+# Output:
+#   slot type=OBJECT name=Suzanne identifier=OBSuzanne

doc/python_api/examples/bpy.types.ActionSlot.3.py

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+"""
+Explicitly Assigning Action Slots
++++++++++++++++++++++++++++++++++
+An action slot is compatible with a data-block if the slot's ``target_id_type`` matches the data-block's type.
+If there are multiple slots on the Action, and you want to just pick the first one that's
+compatible, use the following code. ``anim_data.action_suitable_slots`` can be used `after` the
+Action has been assigned; it is a list of action slots of that Action, but only the ones that
+are actually compatible with the owner of anim_data (in this case, Suzanne).
+
+"""
+# If there are multiple slots on the Action, pick the first one that's compatible
+anim_data = suzanne.animation_data_create()
+anim_data.action = action
+assert anim_data.action_suitable_slots, "expecting at least one suitable slot"
+anim_data.action_slot = anim_data.action_suitable_slots[0]

doc/python_api/examples/bpy.types.ActionSlot.4.py

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+"""
+Finding Action Slot Users
++++++++++++++++++++++++++
+To return a list of the data-blocks that are animated by a specific slot of an Action, use the ``users()`` method of the ActionSlot.
+
+"""
+# Iterate through all actions in the Blender data.
+print("Action & slot users:")
+for action in bpy.data.actions:
+    for slot in action.slots:
+        # Return the data-blocks that are animated by this slot of this action
+        users = slot.users()
+        print(f"{action.name:20} slot={slot.identifier:12s} users: {users}")