Add Sandcastle links to documentation pages

[jjspace]

We have a lot of really useful Sandcastle examples for how to use specific classes. Right now these are hard to discover unless you already know that Sandcastle exists. I think it would be really helpful to add links to sandcastles in the actual documentation alongside class and method definitions to try and help point more people to actual working examples for how to use them.

[lukemckinstry]

Links from documentation would be helpful. Perhaps through a mechanism like tagging there is also a way to make the sandcastle examples searchable by something like a class name.

[jjspace]

The search in sandcastle already searches in the code for every sandcastle itself. This means you can already search for class names and see sandcastles that use it. Some generic searches like Scene will give many results but a search like PostProcess will pull up the specific sandcastles that use the post process stage classes and features