Update Glass choosing field image (#2921)

Matches wpilibsuite/allwpilib#7643
Add new section to make linking easier

source/docs/software/dashboards/glass/field2d-widget.rst

@@ -73,7 +73,9 @@ After sending the ``Field2d`` instance over NetworkTables, the :guilabel:`Field2
 
 Once the widget appears, you can resize and place it on the Glass workspace as you desire. Right-clicking the top of the widget will allow you to customize the name of the widget, select a custom field image, select a custom robot image, and choose the dimensions of the field and robot.
 
-You can choose from an existing field layout using the :guilabel:`Image` drop-down. Or you can select a custom file by setting the :guilabel:`Image` to ``Custom`` and selecting :guilabel:`Choose image...`. You can choose to either select an image file or a PathWeaver JSON file as long as the image file is in the same directory.  Choosing the JSON file will automatically import the correct location of the field in the image and the correct size of the field.
+## Selecting Field Image
+
+You can choose from an existing field layout using the :guilabel:`Image` drop-down. Or you can select a custom file by setting the :guilabel:`Image` to ``Custom`` and selecting :guilabel:`Choose JSON/image...`. You can choose to either select an image file or a PathWeaver JSON file as long as the image file is in the same directory.  Choosing the JSON file will automatically import the correct location of the field in the image and the correct size of the field.
 
 .. note:: You can retrieve the latest field image and JSON files from [here](https://github.com/wpilibsuite/allwpilib/tree/main/fieldImages/src/main/native/resources/edu/wpi/first/fields). This is the same image and JSON that are used when generating paths using :ref:`PathWeaver <docs/software/pathplanning/pathweaver/introduction:Introduction to PathWeaver>`.