Add screenshot to readme.
Add screenshot to readme.

We need to show the UI in the landing page because of a footnote in the
FM paper. There is no space for a screenshot there.

REFS: #

into-cps/intocps-ui,into-cps/intocps-ui,into-cps/intocps-ui,into-cps/intocps-ui,into-cps/intocps-ui