Updated Decal component doc to mention some restrictions when using d…

…ecals. (#2332)

* first draft

Signed-off-by: Ken Pruiksma <pruiksma@amazon.com>

* Moving to separate limitations section.

Signed-off-by: Ken Pruiksma <pruiksma@amazon.com>

* Update content/docs/user-guide/components/reference/atom/decal.md

Co-authored-by: chanmosq <75444793+chanmosq@users.noreply.github.com>
Signed-off-by: Ken Pruiksma <pruiksma@amazon.com>

---------

Signed-off-by: Ken Pruiksma <pruiksma@amazon.com>
Co-authored-by: chanmosq <75444793+chanmosq@users.noreply.github.com>

content/docs/user-guide/components/reference/atom/decal.md

@@ -7,14 +7,18 @@ toc: true
 
 The **Decal** component enables an entity to project a material onto a mesh. A large number of overlapping decals can be applied to a single mesh.
 
-
 ## Provider ##
 
 [Atom Gem](/docs/user-guide/gems/reference/rendering/atom/atom/)
 
+## Limitations ##
 
-## Properties
+There are a few limitations with the Decal component:
+- While decal textures can be any arbitrary resolution, the decal system only supports up to 5 unique texture resolutions. You can create additional decal textures, but the texture resolution must be one of the 5 sizes already in use.
+- All decal materials must specify both a base color and normal map. If any decal material is missing a normal map, then no decals will use a normal map.
+- The base color and normal textures must be the same size.
 
+## Properties
 
 ![Decal component UI](/images/user-guide/components/reference/atom/decal-component-ui/decal-component-ui-01.png)