docs(atomic.conf): sync note about args with spaces with python parser behavior

Author: fkzys

etc/atomic.conf

@@ -13,7 +13,7 @@
 
 # Default command to run in the snapshot chroot (overrides built-in default)
 # Command-line -- CHROOT_COMMAND... overrides this setting
-# Note: args with spaces inside are not supported (simple word splitting)
+# Note: args with spaces inside must be double-quoted (e.g., "package with spaces")
 #CHROOT_COMMAND="/usr/bin/pacman -Syu"
 
 # Sign UKI files with sbctl for Secure Boot (requires sbctl)