added 2 mobile cards for ios and android tutorials (pytorch#1340)

Co-authored-by: Brian Johnson <brianjo@fb.com>

index.rst

@@ -375,6 +375,22 @@ Welcome to PyTorch Tutorials
    :link: advanced/rpc_ddp_tutorial.html
    :tags: Parallel-and-Distributed-Training
 
+.. Mobile
+
+.. customcarditem::
+   :header: Image Segmentation DeepLabV3 on iOS
+   :card_description: A comprehensive step-by-step tutorial on how to prepare and run the PyTorch DeepLabV3 image segmentation model on iOS.
+   :image: _static/img/thumbnails/cropped/ios.png
+   :link: beginner/deeplabv3_on_ios.html
+   :tags: Mobile
+
+.. customcarditem::
+   :header: Image Segmentation DeepLabV3 on Android
+   :card_description: A comprehensive step-by-step tutorial on how to prepare and run the PyTorch DeepLabV3 image segmentation model on Android.
+   :image: _static/img/thumbnails/cropped/android.png
+   :link: beginner/deeplabv3_on_android.html
+   :tags: Mobile
+
 .. End of tutorial card section
 
 .. raw:: html
@@ -550,3 +566,13 @@ Additional Resources
    intermediate/dist_pipeline_parallel_tutorial
    intermediate/rpc_async_execution
    advanced/rpc_ddp_tutorial
+
+.. toctree::
+   :maxdepth: 2
+   :includehidden:
+   :hidden:
+   :caption: Mobile
+
+   beginner/deeplabv3_on_ios.html
+   beginner/deeplabv3_on_android.html
+