Improve suggested location for installing the software in user space

[tlmquintino]

What maintenance does this project need?

According to https://www.freedesktop.org/software/systemd/man/file-hierarchy.html we should suggest to install the software to ~/.local instead of ~/local

Organisation

No response

[TomHodson]

Suggested fix: #12

[TomHodson]

I've also raised the same fix for eckit: ecmwf/eckit#75