[wsrp] public review comment: ExtensionDescription needs expanding

In helping draft a possible extension
to the WSRP v2 protocol, it became clear that ExtensionPart needs an additional
field for the name of the XML element that will carry the extension. The
other option to adding this field would be to require all extension parts
to use an element with the same name as the extension itself. This would
have at least two downsides; 1) If a single WSRP type could be extending
with two different types, deserialization can't key off of the XML element
name, and 2) loss of ability to distinguish semantics of the ExtensionPart
based on its name.

Rich Thompson