Added two more tutorials

Summary:
Added two more tutorials. For mesh rendering and for hand fitting

Also fixed missing copyright in css file

Reviewed By: una-dinosauria

Differential Revision: D63805824

fbshipit-source-id: e232299b1b4572adc9573d441e1d9b34414ac8e3

docs/source/_static/custom.css

+/* Copyright (c) Meta Platforms, Inc. and affiliates.
+
+   This source code is licensed under the MIT license found in the
+   LICENSE file in the root directory of this source tree.
+*/
+
 #rtd-footer-container {
     margin-top: 0px !important;
     margin-bottom: 0px !important;

docs/source/tutorials/index.rst

@@ -13,6 +13,21 @@ Tutorials
    DRTK_Tutorial_2_optimizing_geometry
    DRTK_Tutorial_3_geometry_intersection
 
+.. toctree::
+   :maxdepth: 4
+   :caption: Mesh Rendering
+   :hidden:
+
+   DRTK_Tutorial_rendering_meshes
+
+
+.. toctree::
+   :maxdepth: 4
+   :caption: Computing Gradients and Fitting
+   :hidden:
+
+   DRTK_Tutorial_hand_fitting
+
 .. grid::
 
     .. grid-item-card:: :doc:`DRTK_Tutorial_1_hello_triangle`
@@ -35,3 +50,21 @@ Tutorials
 
         .. image:: ../_static/tutorial_3_animation.gif
           :width: 400
+
+.. grid::
+
+    .. grid-item-card:: :doc:`DRTK_Tutorial_rendering_meshes`
+
+        In this tutorial, we demonstrate how to rendering simple meshes with DRTK.
+
+        .. image:: ../_static/tutorial_rendering_meshes.png
+          :width: 400
+
+.. grid::
+
+    .. grid-item-card:: :doc:`DRTK_Tutorial_hand_fitting`
+
+        In this tutorial, we demonstrate fitting of a simple hand model with simple lambertian material to a single photo.
+
+        .. image:: ../_static/tutorial_hand_fitting.gif
+          :width: 400