X-UA-Compatible meta tag missing, sitemap, and robots.txt example

The X-UA-Compatible meta tag was missing from some HTML files.

robots.txt has an example for allowing all URLs to be crawled, but doesn't have an example for disallowing all URLs to be crawled.

An example sitemap was added. (Though I'm not sure if <loc>http://example.com/</loc> would fly with the Web Starter Kit guidelines.)
@alrra yes, but people might edit it and we still want it to look good no matter how invalid their HTML is. i think it's a good default even though it's not needed with this exact HTML.