Code blocks to support file titles

the ember.js guides support defining a file name with its path as in https://github.com/emberjs/ember.js/blob/04ac480e923ab7f345e30b7aad683bea2ffb7193/packages/ember-glimmer/lib/component.js#L72 and this file path shows up in the code block's title. The API docs fails to do this because the html generated by this tool doesn't support it. We need to add support for the same.