Update genpass documentation in --help and in .conf

bin/xen-create-image

@@ -104,7 +104,12 @@ xen-create-image - Easily create new Xen instances with networking and OpenSSH.
                 fs, size, swap and noswap are ignored when using this
                 option.
 
-   --genpass    Generate a random root password
+   --genpass=1  Generate a random root password
+
+   --genpass-len=N
+                Override the default password length of 8 and generate a
+                random password of length N. Note: this only works in
+                conjunction with --genpass
    
    --password=passphrase
                 Set the root password for the new guest.

etc/xen-tools.conf

@@ -189,10 +189,25 @@ image  = sparse   # Specify sparse vs. full disk images.
 #
 
 #
-# Uncomment the following line if you wish to interactively setup
-# a new root password for images.
+# Uncomment the following line if you wish to generate a new root
+# password for the new guest.
+#
+# genpass = 1
+#
+
+#
+# You can also change the password length by uncommenting and
+# changing the line below
+#
+# genpass_len = 8
+#
+
+#
+# Alternatively, Uncomment the following line if you wish to
+# interactively setup a new root password for images.
 #
 # passwd = 1
+#
 
 #
 # If you'd like all accounts on your host system which are not present