remove the public directory

[ashleymichal]

we want the contents of the worker-site directory to be primarily concerned with how sites are deployed, rather than the content they deploy. the idea of a sample public directory is not necessarily bad, but it should not be adjacent to the other contents of this template; that is, index.js, package.json, and .gitignore will ultimately go into the workers-site directory, and a public directory would be placed as a sibling to that directory.

simplest impl is to just not include this directory. open to other thoughts with the caveat that leaving this will likely demand additional work on the wrangler side.

[EverlastingBugstopper]

we want the public dir