Add detailed documentation for Part.Shape (#900)

## Changes

- Make the table consistent with
https://create.roblox.com/docs/reference/engine/enums/PartType
- Add details about exactness guarantees for part collisions

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---------

Author: Fraktality

content/en-us/reference/engine/classes/Part.yaml

@@ -24,17 +24,20 @@ properties:
       The `Enum.PartType` enum controls the shape value, and has five possible
       shapes:
 
-      | Shape/Value | Description                             |
-      | ----------- | --------------------------------------- |
-      | Ball        | A spherical shape, like a basketball.   |
-      | Cylinder    | A rod-like shape, like a tin can.       |
-      | Block       | The default, brick shape.               |
-      | Wedge       | A wedge shape with a slope on one side. |
-      | CornerWedge | A wedge shape with slopes on two sides. |
+      | Shape/Value | Description                                 |
+      | ----------- | ------------------------------------------- |
+      | Ball        | A spherical shape.                          |
+      | Block       | A block shape.                              |
+      | Cylinder    | A cylinder shape.                           |
+      | Wedge       | A wedge shape with a slope on one side.     |
+      | CornerWedge | A wedge shape with slopes on two sides.     |
 
-      Note that `Class.MeshPart` and
+      `Class.MeshPart` and
       [solid modeling](../../../parts/solid-modeling.md) can be used to obtain
       completely custom part shapes.
+
+      Collisions between balls, blocks, and wedges, and corner wedges are exact, whereas collisions between terrain, cylinders, TriangleMeshes, and other geometry types are approximations.
+      This means that the ball shape can be useful to create stable colliders for car wheels.
     code_samples:
       - using-a-script-to-create-a-part
     type: PartType