[Speech][BatchSynthesis] Fix some inaccurate wording in document (#28883)

* Fix wrong links

* Update batchsynthesis.json

Author: Ling-Cao

specification/cognitiveservices/data-plane/Speech/BatchTextToSpeech/stable/2024-04-01/batchsynthesis.json

@@ -113,7 +113,7 @@
         "tags": [
           "BatchSynthesis"
         ],
-        "description": "Creates a batch synthesis job, the max allowed payload content length is 500KB.",
+        "description": "Creates a batch synthesis job, the max allowed payload content length is 2 megabytes.",
         "operationId": "BatchSyntheses_Create",
         "consumes": [
           "application/json"
@@ -554,7 +554,7 @@
       }
     },
     "Error": {
-      "description": "New format which conforms to the new Cognitive Services API guidelines which is available at https://microsoft.sharepoint.com/%3Aw%3A/t/CognitiveServicesPMO/EUoytcrjuJdKpeOKIK_QRC8BPtUYQpKBi8JsWyeDMRsWlQ?e=CPq8ow. This contains an outer error with error code, message, details, target and an inner error with more descriptive details.",
+      "description": "The error object.",
       "required": [
         "code",
         "message"
@@ -616,7 +616,7 @@
       }
     },
     "InnerError": {
-      "description": "New Inner Error format which conforms to Cognitive Services API Guidelines which is available at https://microsoft.sharepoint.com/%3Aw%3A/t/CognitiveServicesPMO/EUoytcrjuJdKpeOKIK_QRC8BPtUYQpKBi8JsWyeDMRsWlQ?e=CPq8ow.\r\nThis contains required properties ErrorCode, message and optional properties target, inner error(this can be nested).",
+      "description": "An object containing more specific information about the error.",
       "type": "object",
       "properties": {
         "code": {