fix: correct IIS setup step numbering

Steps jumped from 4 to 7, skipping 5 and 6. Renumber to 5 and 6.

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>

Author: somethingwithproof

Installing-Under-Windows.md

@@ -158,7 +158,7 @@ The following changes will be required regardless of your selected Webserver.
 
 4. Under the Documents tab, add `index.php` to the list.
 
-7. Give the IIS user read & execute permissions to the required files
+5. Give the IIS user read & execute permissions to the required files
    file `%windir%\system32\cmd.exe`. They will also need read permissions on
    `cacti_web_root/cacti` and it's subfolders.
    A anm example provided by one user included the following assuming the
@@ -177,7 +177,7 @@ The following changes will be required regardless of your selected Webserver.
    icacls "C:\inetpub\wwwroot\cacti\include\vendor\csrf\csrf-secret.php" /grant "IUSR:(RX,W)"
    ```
 
-8. Completely stop and start the IIS service using the following commands:
+6. Completely stop and start the IIS service using the following commands:
 
    ```batchfile
    net stop iisadmin