message: docs(aio): fix visual-studio-2015 typo
  This fixes
diff: @@ -243,7 +243,7 @@ Everything seems fine while you move about _within_ the app.
  But you'll see the problem right away if you refresh the browser
  or paste a link to an app page (called a "deep link") into the browser address bar.
  -You'll most likely get a *404 - Page Not Found* response from the serer
  +You'll most likely get a *404 - Page Not Found* response from the server
  for any address other than `/` or `/index.html`.
  You have to configure the server to return `index.html` for requests to these "unknown" pages.
  