I do not think there is vsdoc. Could not find it in nuget, and some searches did not call it.
An alternative could be a link to a non-minified version, just like you are referencing a vsdoc file. This could be a list of functions and possibly parameter names.
If you have a good JS tool (many of them are in Extensions Manager), or you have Resharper 6.0, you can go to the function definition or read comments there (the non-minified version has comments, but not in vsdoc format).
Update:
Some common link code to enable intellisense, but not link to the file if you use the nuget package.
http://nuget.org/packages/Backbone.js
Link in Razor file (.cshtml)
@if (false) { <script src="/Scripts/backbone.js" type="text/javascript"></script> }
Link in WebView View Engine (.aspx, .ascx, .master):
<% if(false) { %> <script src="/Scripts/backbone.js" type="text/javascript"></script> <% } %>
Link in JavaScript file (.js)
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