The build documentation currently describes building using MonoDevelop, but it's just as straightforward to use xbuild (once you have Mono installed.) Update the Building documentation to describe this.

Installing dependencies for Ubuntu...
[sudo] password for uuu:
Reading package lists... Done
Building dependency tree
Reading state information... Done
coreutils is already the newest version (8.28-1ubuntu1).
libgoogle-perftools-dev is already the newest version (2.5-2.2ubuntu3).
libleveldb-dev is already the newest version (1.20-2).
libprotobuf-dev is already the newest version (3.0.0-9.1