feat: add a histrical wit-bindgen

__wasm/wit-bindgen-sample/wit-bindgen/crates/parser/tests/ui/embedded.wit.md

@@ -0,0 +1,24 @@
+# A Markdown file!
+
+containing stuff, and also some code blocks, wit and other.
+
+```wit
+x: func()
+```
+
+Intervening content, including a non-wit codeblock:
+```js
+function func() {}
+```
+
+```wit
+y: func()
+```
+
+## A new section
+
+In which, another wit code block!
+
+```wit
+z: func()
+```