stages/ostree: add schema for osname, commit

Add missing schema information for the `osname` and `commit`
options.

stages/org.osbuild.ostree

@@ -30,8 +30,12 @@ the sysroot and the deployments. Additional kernel options can be passed via
 [1] https://ostree.readthedocs.io/en/latest/manual/deployment/
 """
 STAGE_OPTS = """
-"required": ["rootfs"],
+"required": ["commit", "osname", "rootfs"],
 "properties": {
+  "commit": {
+    "description": "checksum of the OSTree commit",
+    "type": "string"
+  },
   "mounts": {
     "description": "Mount points of the final file system",
     "type": "array",
@@ -52,6 +56,10 @@ STAGE_OPTS = """
       }
     }
   },
+  "osname": {
+    "description": "Name of the stateroot to be used in the deployment",
+    "type": "string"
+  },
   "kernel_opts": {
     "description": "Additional kernel command line options",
     "type": "array",