Update service README
Update service README

- Update Status section to reflect rc tag.
- Remove incorrect documentation about geopmwrite
- Remove some implementation details from description

Signed-off-by: Christopher M. Cantalupo <9cf3ecca60a3dd7112ab0e7250bedb8a752e3958@intel.com>

geopm/geopm,geopm/geopm,geopm/geopm,geopm/geopm,cmcantalupo/geopm,geopm/geopm,cmcantalupo/geopm,cmcantalupo/geopm,cmcantalupo/geopm,cmcantalupo/geopm