Better add to homescreen experience across platforms

[bogas04]

Snippet here shows how we can have better support on Safari/Windows and other platforms.

[bogas04]

@shubhnik you can probably take this up. It's easy and adds a lot of value for iPhone users. Basically the goal is to make pinning to home screen work well with Safari on iPhone. Similarly, we need to support PWA on Windows Store. I guess if we can get SikhJS to Windows app store as a PWA, we can gain a lot of users.