If you go to chrome settings -> Manage search engines and define a new search engine with Keyword: "m" and "URL with %s in place of query": https://www.google.com/search?&q=site%3Adeveloper.mozilla.or... typing "m await" in the omnibar will jump to the first google result from MDN, which is what it seems mdn.io does.

https://news.ycombinator.com/item?id=15306429 is my list of custom search engines.