Update README to list librtlsdr alternatives

[ZephyrFanBoy]

The support depends on the librtlsdr used. In short, yes SoapySDR supports the rtlsdr blog v4 but you need an updated librtlsdr (the rtl-sdr libs with v4 support have notes to that).

Originally posted by @zuckschwerdt in #73 (comment)

[zuckschwerdt]

I guess you are asking for this to be documented. Seems a good thing.

[zuckschwerdt]

Perhaps use the results of merbanan/rtl_433#2703 for a section in the README.

[ZephyrFanBoy]

Hi @zuckschwerdt

"I guess you are asking for this to be documented. Seems a good thing." Yes awesome.
Thanks very much. That's useful for me and others noobs.
because rtl-sdr.com has a sub page called " software"
where they explain for some SDR FOSS software how to make it work for the rtlsdrblog v4 usb stick but unfortunatly the pothos flow is not on there.
Perhaps talk to them to get it properly documented.

I am looking into the repository and results of "merbanan/rtl_433" and "osmocom/rtl-sdr"
I am going over the git repo's but there are no releases???
I am looking into the folders, but none have a librtlsdr.dll in there repo?

Another question where is in the pothos SDR directory the location of the librtlsdr.dll v3 that I should replace with the proper librtlsdr.dll v4?
Because searching with explorer I can not find librtlsdr.dll

[zuckschwerdt]

In the bin directory of the Pothos install should be rtlsdr.dll

See https://www.rtl-sdr.com/v4/ for instructions.