[Enhancement] Add a touch icon.

[NiTRoeSE]

Please add a "apple touch Icon".
If you add gitea website as app to homscreen on ios devices there is no icon shown because of missing touch icon.

Sample:

Should be:

It would be nice and of course gitea has it deserved that also a proper icon is displayed :)

Thanks for your work, Gitea is great :)

[zeripath]

For anyone interested in providing a PR for this.

https://www.collectiveray.com/joomla/joomla-tips-and-tricks/94-creating-a-favicon-and-apple-icon-for-your-website.html

seems to describe how to do it...

[silverwind]

Assuming https://realfavicongenerator.net is up to date, it should be one 180px icon:

<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">

We can add it to https://github.com/go-gitea/gitea/blob/master/Makefile#L516

[NiTRoeSE]

@silverwind / @zeripath

Thanks guys for fast reply and commit. 😀