fix-images-in-rl-pulse (#1536)

## Changes
- Fix broken images in https://pennylane.ai/qml/demos/tutorial_rl_pulse

## Preview
- https://pennylane.ai/qml/demos/tutorial_rl_pulse?pr=1536

Author: ashishks0522

…ial_rl_pulse/rl_pulse/DemoOG_RLpulse.png …ation_assets/rl_pulse/DemoOG_RLpulse.pngdemonstrations_v2/tutorial_rl_pulse/rl_pulse/DemoOG_RLpulse.png renamed to _static/demonstration_assets/rl_pulse/DemoOG_RLpulse.png demonstrations_v2/tutorial_rl_pulse/rl_pulse/DemoOG_RLpulse.png renamed to _static/demonstration_assets/rl_pulse/DemoOG_RLpulse.png

@@ -15,7 +15,7 @@
 the main ideas in [#BaumPRXQ21]_, which we illustrate using superconducting qubits as
 an example.
 
-.. figure:: ../demonstrations/rl_pulse/DemoOG_RLpulse.png
+.. figure:: ../_static/demonstration_assets/rl_pulse/DemoOG_RLpulse.png
    :align: center
    :width: 60%
 
@@ -79,7 +79,7 @@
 how well the agent is performing the task given the last interaction. We will see more about the
 reward in the following section.
 
-.. figure:: ../demonstrations/rl_pulse/sketch_rl.png
+.. figure:: ../_static/demonstration_assets/rl_pulse/sketch_rl.png
    :align: center
    :width: 75%
 
@@ -127,7 +127,7 @@
 segments are now fixed, we proceed with the evaluation of the pulse with respect to the target gate
 that we wish to execute.
 
-.. figure:: ../demonstrations/rl_pulse/sketch_protocol.png
+.. figure:: ../_static/demonstration_assets/rl_pulse/sketch_protocol.png
    :align: center
    :width: 90%