add a new c# sample for PII eradication from documents

sdk/textanalytics/Azure.AI.TextAnalytics/samples/Sample13_EradicatePiiDocument.md

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+# Recognizing Personally Identifiable Information in Documents
+
+This sample demonstrates how to eradicate Personally Identifiable Information (PII) from one or more native documents.
+
+A native document refers to the file format used to create the original document such as Microsoft Word (docx) or a portable document file (pdf). Native document support eliminates the need for text preprocessing before using Azure AI Language resource capabilities. 
+
+Language resource needs granted access to your storage account
+``` private static readonly HttpClient httpClient = new HttpClient();
+    private const string CognitiveServicesUrl = "https://<endpointname>.cognitiveservices.azure.com/language/analyze-documents/jobs?api-version=2024-11-15-preview";
+    private const string SourceSasUri = "<containersasuri>";
+    private const string DestinationSasUri = "containersasuri";
+```
+
+Iterate through the files in the source container, filter out PDF and DOCX files, append the file name to the source SAS URI, and then invoke the cognitive service.
+``` private static async Task ProcessSourceContainerAsync()
+    {
+        BlobContainerClient sourceContainer = new BlobContainerClient(new Uri(SourceSasUri));
+        await foreach (var blobItem in sourceContainer.GetBlobsAsync())
+        {
+            if (blobItem.Name.EndsWith(".pdf") || 
+                blobItem.Name.EndsWith(".docx"))
+            {
+                string blobUri = sourceContainer.Uri.ToString().Replace("?", "/" + Uri.EscapeDataString(blobItem.Name) + "?");
+                await AnalyzeDocumentAsync(blobUri);
+                await Task.Delay(TimeSpan.FromSeconds(2));
+                Console.WriteLine(blobItem.Name);
+            }
+        }
+    }
+```
+
+Call the service to eradicate the PII from document
+```
+    private static async Task AnalyzeDocumentAsync(string sourceUri)
+    {
+        var requestBody = new
+        {
+            displayName = "Document PII Redaction example",
+            analysisInput = new
+            {
+                documents = new[]
+                {
+                    new
+                    {
+                        language = "en-US",
+                        id = "Output-1",
+                        source = new { location = sourceUri },
+                        target = new { location = DestinationSasUri }
+                    }
+                }
+            },
+            tasks = new[]
+            {
+                new
+                {
+                    kind = "PiiEntityRecognition",
+                    taskName = "Redact PII Task 1",
+                    parameters = new
+                    {
+                        redactionPolicy = new { policyKind = "EntityMask" },
+                        excludeExtractionData = false,
+                        piiCategories = new [] {
+                            "Person",
+                            "Organization", 
+                            "PersonType", 
+                            "PhoneNumber",
+                            "Organization", 
+                            "Address",
+                            "Email",
+                            "URL",
+                            "IPAddress",
+                            "DateTime",
+                            "Date",
+                            "Age",
+                        }
+                    }
+                }
+            }
+        };
+
+        string jsonContent = JsonSerializer.Serialize(requestBody);
+        HttpContent content = new StringContent(jsonContent, Encoding.UTF8, "application/json");
+        content.Headers.Add("Ocp-Apim-Subscription-Key", "<key>");
+        HttpResponseMessage response = await httpClient.PostAsync(CognitiveServicesUrl, content);
+        foreach (var header in response.Headers)
+        {
+            Console.WriteLine($"{header.Key}: {string.Join(", ", header.Value)}");
+        }
+        Console.WriteLine(await response.Content.ReadAsStringAsync());
+        if (response.IsSuccessStatusCode)
+        {
+            Console.WriteLine("Success: " + response.Headers);
+        }
+        else
+        {
+
+            Console.WriteLine("Failed: " + response.StatusCode);
+        }
+    }
+```
+
+
+    static async Task Main()
+    {
+        await ProcessSourceContainerAsync();
+    }
+```
+
+}
+
+