doc: qvm-create-default-dvm (#940)

doc/qvm-tools/qvm-create-default-dvm.rst

@@ -10,7 +10,24 @@ qvm-create-default-dvm - creates a default disposable VM
 
 SYNOPSIS
 ========
-| qvm-create-default-dvm
+| qvm-create-default-dvm templatename|--default-template|--used-template [script-name|--default-script]
+
+OPTIONS
+=======
+templatename
+    Base DispVM on given template. The command will create AppVM named after
+    template with "-dvm" suffix. This VM will be used to create DispVM
+    savefile. If you want to customize DispVM, use this VM - take a look at
+    https://wiki.qubes-os.org/wiki/UserDoc/DispVMCustomization
+
+--default-template
+    Use default template for the DispVM
+
+--used-template
+    Use the same template as earlier
+
+--default-script
+    Use default script for seeding DispVM home.
 
 
 AUTHORS