[ReleasePR search] [Azure Cognitive Search] Fix typos and add some descriptins (#1783)

Create to sync Azure/azure-rest-api-specs#14903
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/master...AzureSDKAutomation:sdkAuto/search?expand=1)

Author: msftbot[bot]

schemas/2021-04-01-preview/Microsoft.Search.json

@@ -22,7 +22,7 @@
               "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
             }
           ],
-          "description": "Identity for the resource."
+          "description": "Details about the search service identity. A null value indicates that the search service has no identity assigned."
         },
         "location": {
           "type": "string",
@@ -197,7 +197,7 @@
           "description": "Describes what response the data plane API of a Search service would send for requests that failed authentication."
         }
       },
-      "description": "Indicates that either the API key or an access token from AAD can be used for authentication."
+      "description": "Indicates that either the API key or an access token from Azure Active Directory can be used for authentication."
     },
     "DataPlaneAuthOptions": {
       "type": "object",
@@ -211,7 +211,7 @@
               "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
             }
           ],
-          "description": "Indicates that either the API key or an access token from AAD can be used for authentication."
+          "description": "Indicates that either the API key or an access token from Azure Active Directory can be used for authentication."
         },
         "apiKeyOnly": {
           "type": "object",
@@ -276,13 +276,13 @@
               "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
             }
           ],
-          "description": "The list of user identities associated with the resource. The user identity dictionary key references will be ARM resource ids in the form: '/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.ManagedIdentity/userAssignedIdentities/{identityName}'."
+          "description": "The list of user identities associated with the search service. The user identity dictionary key references will be ARM resource ids in the form: '/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.ManagedIdentity/userAssignedIdentities/{identityName}'."
         }
       },
       "required": [
         "type"
       ],
-      "description": "Identity for the resource."
+      "description": "Details about the search service identity. A null value indicates that the search service has no identity assigned."
     },
     "IpRule": {
       "type": "object",
@@ -427,7 +427,7 @@
               "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
             }
           ],
-          "description": "A list of data exfiltration scenarios that are explicitly disallowed for the search service."
+          "description": "A list of data exfiltration scenarios that are explicitly disallowed for the search service. Currently, the only supported value is 'All' to disable all possible data export scenarios with more fine grained controls planned for the future."
         },
         "disableLocalAuth": {
           "oneOf": [
@@ -534,7 +534,7 @@
               "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
             }
           ],
-          "description": "Defines the SKU type for the semantic search feature enabled for the search service."
+          "description": "Sets options that control the availability of semantic search. This configuration is only possible for certain Azure Cognitive Search SKUs in certain locations."
         }
       },
       "description": "Properties of the search service."
@@ -703,7 +703,7 @@
     "UserAssignedManagedIdentity": {
       "type": "object",
       "properties": {},
-      "description": "The details of the user assigned managed identity used by the Video Analyzer resource."
+      "description": "The details of the user assigned managed identity assigned to the search service."
     }
   }
 }