Expand on how to install the library

[lu-zero]

Suggest to use --destdir and then sudo cp the files.

See: #2928

[tdaede]

Should probably use the install binary rather than cp to get proper permissions set.

There's also an incantation of cargo cinstall that I managed to install directly with, I can try to find it.

[lu-zero]

cargo cinstall does not know about permission, I might add yet another feature to deal with that maybe.

[lu-zero]

If you have ready the install command I can add it as well.

[lu-zero]

It should be otherwise covered