bug#56885: Fix url-about.el in EWW or make it obsolete

[Po Lu]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> `url-proxy-services' is a normal defcustom, so you can view it via `C-h
> v' or Customize, like any other variable.

It's certainly not as pleasant to view that way as in the neatly
formatted about:protocols page.

> Having about:foo in url.el is cute, but it emulates browsers that had
> no other way to specify stuff like this.  Emacs is much more powerful
> than that.

But why is such "power" a reason to remove the about:protocols URL? What
harm is being done by keeping it there?