[Batch] Make readme.md and swagger titles consistent (#15424)

* [Batch] Changed "title" from BatchManagement to BatchManagementClient

Autorest is using this to generate the name of the client class. Changing this will avoid a breaking change in the Java SDK that is about to be released.

* Make readme.md titles consistent with swagger

Author: dpwatrous

specification/batch/data-plane/Microsoft.Batch/stable/2021-06-01.14.0/BatchService.json

@@ -1,7 +1,7 @@
 {
   "swagger": "2.0",
   "info": {
-    "title": "BatchService",
+    "title": "BatchServiceClient",
     "version": "2021-06-01.14.0",
     "description": "A client for issuing REST requests to the Azure Batch service."
   },

specification/batch/resource-manager/Microsoft.Batch/stable/2021-06-01/BatchManagement.json

@@ -1,7 +1,8 @@
 {
   "swagger": "2.0",
   "info": {
-    "title": "BatchManagement",
+    "title": "BatchManagementClient",
+    "description": "The Batch Management Client.",
     "version": "2021-06-01"
   },
   "host": "management.azure.com",

specification/batch/resource-manager/readme.md

@@ -25,6 +25,8 @@ To see additional help and options, run:
 These are the global settings for the Batch API.
 
 ``` yaml
+title: BatchManagementClient
+description: Batch Client
 openapi-type: arm
 tag: package-2021-06
 ```