Update create-key-vault-for-code-signing.md

replace p12 with pfx when uploading to Key Vault

Author: clromano

powerapps-docs/maker/common/wrap/create-key-vault-for-code-signing.md

@@ -83,7 +83,7 @@ In this article, you will learn how to use an existing Azure Key Vault or create
           - Mac: base64 `-i example.mobileprovision`
           - Windows:  `certutil -encode data.txt tmp.b64`
 
-       4. Upload the `base64` string obtained from the previous step to the Key Vault secret. Next, upload the .p12 file to Key Vault Certificate.
+       4. Upload the `base64` string obtained from the previous step to the Key Vault secret. Next, upload the .pfx file to Key Vault Certificate.
 
 
           :::image type="content" source="media/wrap-canvas-app/wrap-2.png" alt-text="Create a cert for iOS.":::