Acknowledge PiSDR as an impetus for this effort + source of SDR packages

[vielmetti]

Luigi PU2SPY @luigifcruz has a PiSDR image for the Raspberry Pi.

https://github.com/luigifcruz/pisdr-image

The PiSDR is a Raspbian based operating system for the Pi pre-loaded with multiple Software Defined Radio software. It was created to serve as a fast and reliable bootstrap for SDR projects.

The distribution is notable for its support for a wide range of SDR hardware and software, which is documented in the image build. Software is installed out of apt but more often built from Github repositories. The relevant directory with build instructions and code is in the "stage4" directory at https://github.com/luigifcruz/pisdr-image/tree/9bf154df78743ed9419e29510acc53df2e9a5506/stage4

ferrite is unlikely to have anywhere near the comprehensive set of SDR packages that PiSDR has accumulated, and doesn't look to get all of the SDR hardware support out of the box, but it's a place to start to look first.