add: Comment based help to new sync function and output type added

source/Public/Sync-CISExcelAndCsvData.ps1

@@ -1,4 +1,34 @@
+<#
+    .SYNOPSIS
+    Synchronizes and updates data in an Excel worksheet with new information from a CSV file, including audit dates.
+    .DESCRIPTION
+    The Sync-CISExcelAndCsvData function merges and updates data in a specified Excel worksheet from a CSV file. This includes adding or updating fields for connection status, details, failure reasons, and the date of the update. It's designed to ensure that the Excel document maintains a running log of changes over time, ideal for tracking remediation status and audit history.
+    .PARAMETER ExcelPath
+    Specifies the path to the Excel file to be updated. This parameter is mandatory.
+    .PARAMETER CsvPath
+    Specifies the path to the CSV file containing new data. This parameter is mandatory.
+    .PARAMETER SheetName
+    Specifies the name of the worksheet in the Excel file where data will be merged and updated. This parameter is mandatory.
+    .EXAMPLE
+    PS> Sync-CISExcelAndCsvData -ExcelPath "path\to\excel.xlsx" -CsvPath "path\to\data.csv" -SheetName "AuditData"
+    Updates the 'AuditData' worksheet in 'excel.xlsx' with data from 'data.csv', adding new information and the date of the update.
+    .INPUTS
+    System.String
+    The function accepts strings for file paths and worksheet names.
+    .OUTPUTS
+    None
+    The function directly updates the Excel file and does not output any objects.
+    .NOTES
+    - Ensure that the 'ImportExcel' module is installed and up to date to handle Excel file manipulations.
+    - It is recommended to back up the Excel file before running this function to avoid accidental data loss.
+    - The CSV file should have columns that match expected headers like 'Connection', 'Details', 'FailureReason', and 'Status' for correct data mapping.
+    .LINK
+    https://criticalsolutionsnetwork.github.io/M365FoundationsCISReport/#Sync-CISExcelAndCsvData
+#>
+
 function Sync-CISExcelAndCsvData {
+    [OutputType([void])]
+    [CmdletBinding()]
     param(
         [string]$ExcelPath,
         [string]$CsvPath,