Add useAcrylicInTabRow to JSON schema (#11117)

`useAcrylicInTabRow` was missing from the JSON schema, so I added it in.

## References
#10864 

## PR Checklist
* [x] Closes #11087 
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] Schema updated.

doc/cascadia/profiles.schema.json

@@ -1260,6 +1260,11 @@
           "default": "false",
           "description": "When set to true, the Terminal's tray icon will always be shown in the system tray.",
           "type": "boolean"
+        },
+        "useAcrylicInTabRow": {
+          "default": "false",
+          "description": "When set to true, the tab row will have an acrylic background with 50% opacity.",
+          "type": "boolean"
         },
 		"actions": {
 			"description": "Properties are specific to each custom action.",