ui: pool view: replace allow-transfer checkbox with simple hint

It's not really providing good UX, as user needs to extra tick this
but cannot be sure what transfer means in this case.

Just replace this with a simple, more telling hint that will inform
users about what happens.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

www/manager6/grid/PoolMembers.js

@@ -1,9 +1,15 @@
 Ext.define('PVE.pool.AddVM', {
     extend: 'Proxmox.window.Edit',
+
     width: 600,
     height: 420,
     isAdd: true,
     isCreate: true,
+
+    extraRequestParams: {
+	transfer: 1,
+    },
+
     initComponent: function() {
 	var me = this;
 
@@ -90,15 +96,17 @@ Ext.define('PVE.pool.AddVM', {
 	    ],
 	});
 
-	let transfer = Ext.create('Ext.form.field.Checkbox', {
-	    name: 'transfer',
-	    boxLabel: gettext('Allow Transfer'),
-	    inputValue: 1,
-	    value: 0,
-	});
 	Ext.apply(me, {
 	    subject: gettext('Virtual Machine'),
-	    items: [vmsField, vmGrid, transfer],
+	    items: [
+		vmsField,
+		vmGrid,
+		{
+		    xtype: 'displayfield',
+		    userCls: 'pmx-hint',
+		    value: gettext('Selected guests who are already part of a pool will be removed from it first.'),
+		},
+	    ],
 	});
 
 	me.callParent();