Update .gitattributes

.gitattributes

@@ -2,3 +2,8 @@
 *.md linguist-generated=false
 *.md linguist-documentation=false
 *.md linguist-detectable=true
+
+*.xaml linguist-vendored=false
+*.xaml linguist-generated=false
+*.xaml linguist-documentation=false
+*.xaml linguist-detectable=true