state: describe OperatingSystemState and BootProgress in README.md

This commit updates the state README file with Operating System
and Boot Progress states. The host state dbus object already
implements both the properties but the documentation in the README
did not describe why the property had to be implemented. This commit
is improving the readme by adding the documentation.

Change-Id: I047e9d55dcabb6d79dbdad7ff9f666ee3355cd5b
Signed-off-by: Sampa Misra <sampmisr@in.ibm.com>
1 file changed