[Bug-gnuzilla] clarify if icecatmobile is associated with gnu icecat

[Ian Kelling]

https://f-droid.org/packages/org.gnu.icecat/ On that page, it's using
the icecat logo, it links to the gnu icecat page as it's homepage, but
it says bug tracking is at mozilla's page, and source code is at
mozilla's page, which is clearly wrong, mozilla is not distributing
sources that include the icecat logo and name.

The gnu icecat page says releases are at
http://ftp.gnu.org/gnu/gnuzilla/, but there are only x86 architecture
releases, and doesn't mention "icecatmobile" anywhere.

There are multiple issues, the biggest being that we have icecatmobile
with no source code available to download (i assume it's available
somewhere, just undocumented).