Reorganize and rewrite examples

This commit is a large-ish scale reorganization of our examples. The
main goal here is to have a dedicated section of the guide for example,
and all examples will be listed there. Each example's `README` is now
just boilerplate pointing at the guide along with a blurb about how to
run it.

Some examples like `math` and `smorgasboard` have been deleted as they
didn't really serve much purpose, and others like `closures` have been
rewritten with `web-sys` instead of hand-bound bindings.

Overall it's hoped that this puts us in a good and consistent state for
our examples, with all of them being described in the guide, excerpts
are in the guide, and they're all relatively idiomatically using
`web-sys`.

examples/no_modules/README.md

@@ -1,10 +1,15 @@
-# `--no-modules`
+# Using `--no-modules`
 
-This directory is an example of using the `--no-modules` flag and how it
-integrates with the rest of the HTML/JS used.
+[View documentation for this example online][dox]
+
+[dox]: https://rustwasm.github.io/wasm-bindgen/examples/no-modules.html
 
 You can build the example locally with:
 
 ```
 $ ./build.sh
 ```
+
+(or running the commands on Windows manually)
+
+and then opening `index.html` in a browser should run the example!