Add some notes about importing meshes for use with SoftBody3D

This mentions that users may want to change the default LOD generation
settings when importing meshes for use with SoftBody3D.

See godotengine/godot#108025

Author: simpkins

tutorials/physics/soft_body.rst

@@ -67,3 +67,21 @@ Play the scene and the cloak should simulate correctly.
 .. image:: img/softbody_cloak_finish.png
 
 This covers the basic settings of softbody, experiment with the parameters to achieve the effect you are aiming for when making your game.
+
+Using Imported Meshes
+~~~~~~~~~~~~~~~~~~~~~
+
+The **Save to File** option in the Advanced Import Settings dialog allows you
+to save a mesh to a standalone resource file that you can then attach to
+``SoftBody3D`` nodes.
+
+You may also want to disable LOD generation or change the LOD generation options
+when importing a mesh for use with ``SoftBody3D.`` The default import settings
+will produce an LOD that merges adjacent faces that are nearly flat with
+respect to each other, even at very close render distances. This works well for
+static meshes, but is often undesirable for use with ``SoftBody3D`` if you want
+these faces to be able to bend and move with respect to each other, instead of
+being rendered as a single plane.
+
+See :ref:`doc_importing_3d_scenes_import_configuration` and :ref:`doc_mesh_lod`
+for more details.