docs: Remove out of date examples

The examples in the RTIO docs were nice but continuously became out of
date without being updated. This is unfortunately the downside of
doc-only samples like this.

Some real, buildable, samples right be better but will take a little
time to write up. In the meantime drop the examples in the docs to avoid
confusion.

Signed-off-by: Tom Burdick <thomas.burdick@intel.com>