Add documentatin site example
* Repurpose the third example for documentation
* No need for a separate route type
We can repurporse the source path as route.
* Add markdown parser via commonmark
* Read .md files recursively
* Add Ema.Helper.FileSystem (fsnotify code)
* Pandoc Blaze renderer (not complete)
* Rewrite links in Pandoc AST to use routes
* Start syling AST elements
* Basic breadcrumbs
* finalize
