Adding schema to colleciton

Author: glenrobson

schema/iiif_3_0.json

@@ -519,6 +519,22 @@
                 {
                     "type": "object",
                     "properties": {
+                        "@context": {
+                            "oneOf": [
+                                {
+                                    "type": "array",
+                                    "items": {
+                                        "type": "string",
+                                        "format": "uri",
+                                        "pattern": "^http.*$"
+                                    }
+                                },
+                                {
+                                    "type": "string",
+                                    "const": "http://iiif.io/api/presentation/3/context.json"
+                                }
+                            ]
+                        },
                         "type": {
                             "type": "string",
                             "pattern": "^Collection",