Support PWA for offline documentation usage

Hi there,

Saw that #4526 addressed this, and that the OP actually went ahead and submitted merge request #4530. The merge request was rejected because it was unknown what the tradeoffs of including a manifest and service worker were.

I wanted to maybe restart the conversation on this, I think it'd be beneficial to have the docs be available in their original format for offline consumption. There are obviously work arounds (cloning and serving the site locally, offline docs providers), but both of those have fairly significant drawbacks and aren't as easy as right click installing the page.

Bắt đầu bằng việc xem xét issue #4526 và merge request #4530, bao gồm lý do đề xuất trước đó bị từ chối. Đánh giá những đánh đổi khi thêm web manifest và service worker, sau đó xác định khả năng cung cấp tài liệu khi ngoại tuyến và việc cài đặt nên cung cấp những gì trước khi bắt đầu triển khai.