updates Assently E-Sign updateCase action (#1232)

* Adds Assently E-Sign custom connector for certification

* fixes bug of getting file content of Assently case documents

* Updates Assently readme file.

* updates Assently E-Sign updateCase action

certified-connectors/Assently E-Sign/apiDefinition.swagger.json

@@ -258,13 +258,9 @@
             "in": "body",
             "required": true,
             "schema": {
-              "x-ms-dynamic-schema": {
-                "parameters": {
-                  "schemaType": "caseModel"
-                },
-                "operationId": "GetSchema",
-                "value-path": "schema"
-              }
+              "type": "object",
+              "x-ms-visibility": "important",
+              "title": "Case object to be updated"
             }
           }
         ]