Update reference to qvm-trim-template for R4+

Fixes QubesOS/qubes-issues#5260

os-guides/pentesting/kali.md

@@ -148,15 +148,9 @@ There are multiple ways to create a Kali Linux VM:
        [user@kali ~]$ sudo apt-get dist-upgrade
        [user@kali ~]$ sudo apt-get autoremove
 
-8. Shutdown and trim `kali` template
+8. Shut down `kali` template
 
-    - Shutdown `kali` template
-
-            [user@kali ~]$ sudo shutdown -h now
-
-    - In `dom0` console:
-
-            [user@dom0 ~]$ qvm-trim-template kali
+       [user@kali ~]$ sudo shutdown -h now
 
 9. Start image
 
@@ -285,10 +279,9 @@ These instructions will show you how to upgrade a Debian TemplateVM to Kali Linu
         [user@kali-rolling ~]$ sudo apt-get dist-upgrade
         [user@kali-rolling ~]$ sudo apt-get autoremove
  
-9. Shut down and trim the new template.
+9. Shut down the new template.
 
         [user@dom0 ~]$ qvm-shutdown kali-rolling
-        [user@dom0 ~]$ qvm-trim-template kali-rolling
 
 10. Ensure a terminal can be opened in the new template.