Link Intune tutorial to evergreen .intunewin URLs

The files.smallstep.com/intune/ copy is updated by hand and had gone
stale. Point at the stable-channel _latest pointers on
packages.smallstep.com instead (written on every promotion by
smallstep/agent#1207), and link the arm64 package directly now that
it ships from CI.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W3b91ygScLGY4tpBtzUsG4

Author: tashian

tutorials/connect-intune-to-smallstep.mdx

@@ -101,7 +101,7 @@ In this step, we’ll add the Smallstep Agent to Intune for distribution to devi
 1. In Intune,
     1. Start at [Windows Apps](https://intune.microsoft.com/#view/Microsoft_Intune_DeviceSettings/AppsWindowsMenu/~/windowsApps)
     2. Choose **+ Create**, and then select **Windows App (Win32)**
-    3. [Download the Smallstep agent `.intunewin` package for `amd64`](https://files.smallstep.com/intune/step-agent-plugin_amd64.intunewin) and select it for upload in Intune. (Contact Smallstep if you need an `arm64` installer).
+    3. Download the Smallstep agent `.intunewin` package for [`amd64`](https://packages.smallstep.com/stable/windows/step-agent_amd64_latest.intunewin) or [`arm64`](https://packages.smallstep.com/stable/windows/step-agent_arm64_latest.intunewin) and select it for upload in Intune.
     - For the App Information tab:
         - For Publisher, use “Smallstep”
         - Note the version number. You'll need it below.