Fix install_linux.sh paths

[mikkovedru]

Otherwise the instuctions of:

$ cd util
$ bash ./install_linux.sh

will lead to copying path errors:

cp: cannot stat './fonts/otf/*': No such file or directory
cp: cannot stat './fonts/variable/*': No such file or directory

[cloudishBenne]

The more simple solution would be to just change the instruction command to:

bash util/install_linux.sh

[idan]

Fixed in the batch of commits around 93c4bcdb772fe34c4aef415a87e1521ae9947012. Thank you!