Update README.md
Update README.md
Update README.md
Update README.md
minor updates, added some sub sections to index
spell checked these docs ;)
ioHubExperimentRuntime doc'ed
Rewrites on index page
doc'ed Computer Device.

- partial doc of devices.rst and classes ref'ed from it, not done yet.
doc'ed devices.rst and classes refernced from it

-classes doc'ed:
Device
Device Event