lava-expect: fix successes strings in interactive actions

Fixes some wrongly placed successes strings and instead use only
prompts for better readability. Also, fix and re-phrase some
paragraphs in the readme section for better understanding.

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: Ia4a8f0a771d23d45f77778d3bfa1b28cc9051d34
5 files changed