Imporve Build Instructions

[Karlosbubi]

Is your feature request related to a problem? Please describe.

The build instructions are a bit to compact and not entirely correct.

Describe the solution you'd like

Polish the build script as well as the readme.

E.g.:

Readme states ./.github/scripts/build-linux.sh but that results in bash: ./.github/scripts/build-linux.sh: No such file or directory since the symlink doesn't have the .sh suffix.

Also unlike suggested by the wrong .sh suffix it can not be executed using sh, not even unsing bash. It depends on zsh which isn't mentioned and not usually present on most distros, including Ubuntu which is specified in the readme.

Also it would be nice to support more distros. ✖︎ No apt-get command found. Please install apt, there aren't any fully manual instructions for other people either.