schema/defs.json: Pull ociVersion over from config-schema.json

So we can use it in the coming state-schema.json without duplication.
While I'm touching it, I updated the spec title to match the project
README's header.  I also dropped the "id" because none of the other
defs.json entries had an ID.

Signed-off-by: W. Trevor King <wking@tremily.us>

schema/config-schema.json

@@ -5,9 +5,8 @@
     "type": "object",
     "properties": {
         "ociVersion": {
-            "description": "The version of OpenContainer specification configuration complies with",
             "id": "https://opencontainers.org/schema/bundle/ociVersion",
-            "type": "string"
+            "$ref": "defs.json#/definitions/ociVersion"
         },
         "hooks": {
             "id": "https://opencontainers.org/schema/bundle/hooks",

schema/defs.json

@@ -155,6 +155,10 @@
                 "source",
                 "type"
             ]
+        },
+        "ociVersion": {
+            "description": "The version of Open Container Runtime Specification that the document complies with",
+            "type": "string"
         }
     }
 }