FTP release site and documentation on building releases

[abradd]

I've seen references to an FTP server for downloading iverilog releases at ftp://ftp.icarus.com/pub/eda/verilog/. It seems that server is no longer accessible, though there is still some outdated documentation pointing to it. I couldn't find any announcement or documentation that declared the FTP server defunct, though it is no longer referenced in the official docs.

In the README, under the "Compiling from Release" section the instructions are:

  ./configure
  make

The only releases I could find were the Github releases which seem to need sh autoconf.sh to be run on them. Perhaps the old releases has the configure script already available.