Convert command to Powershell

Author: JackStuart

defender-office-365/tenant-allow-block-list-files-configure.md

@@ -41,6 +41,9 @@ This article describes how admins can manage entries for files in the Microsoft
   ```DOS
   certutil.exe -hashfile "<Path>\<Filename>" SHA256
   ```
+```powershell
+ Get-FileHash -Path "<Path>\Filename>" -Algorithm SHA25
+```
 
   An example value is `768a813668695ef2483b2bde7cf5d1b2db0423a0d3e63e498f3ab6f2eb13ea3a`. Perceptual hash (pHash) values aren't supported.