update readme

Author: yorkie

README.md

@@ -27,9 +27,9 @@ Like the classic Web browser, it supports not only the HTML document, but also l
 | SVG      | Not started | Displaying SVG images        |
 | GLTF     | Ok          | Displaying 3D models         |
 | JPEG/PNG | Ok          | Viewing images               |
-| XSML     | Ok          | Using WebXR applications     |
+| XSML     | Deprecated  | Using WebXR applications     |
 
-> XSML: namely eXtensible Spatial Markup Language, is a new format that is designed for spatial applications for HTML developers.
+> XSML: namely eXtensible Spatial Markup Language, is a new format that is designed for spatial applications for HTML developers but deprecated.
 
 ### Scripting & Modules