Running RVfpga v2.1 with Ubuntu OS 20:04 (LTS version)

A useful update from Daniel Chaver-Martinez:

We have tested the RVfpga v2.1 materials (GSG + Labs 1-20) in a Ubuntu 20.04.3 OS, and everything works correctly.
Just some notes:

• At the beginning of the installation of Vivado 2019.2 you will get the following warning: “Not supported OS”.
  -->You can simply ignore this warning and go ahead with the installation. Vivado should work correctly.
• You may experience problems with the “git clone” command. In that case, please refer to the following forum post:
  https://university.imgtec.com/forums/rvfpga/problems-with-the-git-clone-of-verilator/
• The Verilator repo is mirrored on github as well: https://github.com/verilator/verilator [github.com]