Remove "gvp:expr" <grammar> attribute

SUMMARY: Remove the "gvp:expr" <grammar> attribute from the help document

The next publication of the GVP 8.1 Voice XML Help will include this revision:

TOPIC: VoiceXML Tags
SECTION: <Grammar>
Description:
The "GVP 8.1 Voice XML Help" document contains the "gvp:expr" <grammar> attribute. This should be removed as it only worked with VGi and non-vxml 2.1. Delete the following information from the document:

(Optional) This attribute is an ECMAScript expression to be evaluated and used as the initial value of this grammar. This record will be visited only if the expression evaluates to undefined.

The default value is undefined.

This attribute is a GVP extension and must be qualified by the GVP-namespace when used in the tag.