Update readme for building.

[Alex313031]

The readme currently says

sensors
hwloc
libcap (v2.21 or later)
libnl-3

, but it should say libsensors4-dev, libhwloc-dev, libcap-dev, and libnl-3-dev

[fasterit]

We don't say what the package names are as they are specific to distributions. I.e. your list will not work on Red Hat distros.