remove references to older schema drafts (#243)

Author: mkhraisha

example/yaml-json-schema.yaml

@@ -12,11 +12,11 @@ properties:
         type: string
         format: email
     required:
-    - emailAddress
+      - emailAddress
 example: |-
   {
     "$id": "https://example.com/schemas/email.json",
-    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
     "title": "EmailCredential",
     "description": "Email Credential JSON Schema",
     "type": "object",
@@ -32,4 +32,4 @@ example: |-
         "required": ["emailAddress"]
       }
     }
-  }
+  }

index.html

@@ -518,18 +518,6 @@ <h2>JSON Schema Specifications</h2>
                    <td><a href="https://json-schema.org/draft/2020-12/schema">https://json-schema.org/draft/2020-12/schema</a></td>
                    <td>Yes</td>
                 </tr>
-                <tr>
-                   <td>[[?JSON-SCHEMA-2019-09]]</td>
-                   <td>19 March 2020</td>
-                   <td><a href="https://json-schema.org/draft/2019-09/schema">https://json-schema.org/draft/2019-09/schema</a></td>
-                   <td>No</td>
-                </tr>
-                <tr>
-                   <td>[[?JSON-SCHEMA-DRAFT-7]]</td>
-                   <td>20 September 2018</td>
-                   <td><a href="http://json-schema.org/draft-07/schema#">http://json-schema.org/draft-07/schema#</a></td>
-                   <td>No</td>
-                </tr>
              </tbody>
           </table>
 

schema/json-schema-credential-schema.json

@@ -19,17 +19,7 @@
           "const": "JsonSchema"
         },
         "jsonSchema": {
-          "anyOf": [
-            {
-              "$ref": "https://json-schema.org/draft/2020-12/schema"
-            },
-            {
-              "$ref": "https://json-schema.org/draft/2019-09/schema"
-            },
-            {
-              "$ref": "http://json-schema.org/draft-07/schema"
-            }
-          ]
+          "$ref": "https://json-schema.org/draft/2020-12/schema"
         }
       },
       "required": [