documentation: Document the 1.0 API
documentation: Document the 1.0 API

The virtcontainers godoc [1] does not highlight the 1.0 top level API
in a readable and clear way. This API documentation attempts to
provide a top to bottom description of the virtcontainers 1.0 API.

[1] https://godoc.org/github.com/containers/virtcontainers

Signed-off-by: Samuel Ortiz <0ba86cb3f08bbb861958e54bd3438887adb4263c@linux.intel.com>

containers/virtcontainers,containers/virtcontainers