example: Deprecate the webusb package dependency

[windowsair]

The webusb feature is already included in the usb package. Let's deprecate the extra webusb package.

[thegecko]

Sorry for the delay replying here. By adding a dependency on node-usb in the examples it stops it from working in a browser environment.
We need to ensure dapjs can be used in the web (it's original intent) as well as on the desktop with node-usb poly-filling webusb

Please comment if I've missed a point!

[windowsair]

In the folder for each example there is a web.html, they should not depend on any other js file except dapjs, I'm not sure if this is what you want?

[thegecko]

I'm keen web users don't assume they need to download node-usb to use the examples.

Perhaps a better approach would be to reorganise the examples into web ones and desktop ones?

[windowsair]

I think it's better to update the documentation. Some of the content in the current documentation is no longer applicable.