Add more UI screenshots to the website

[yurishkuro]

We don't feature the UI screenshots prominently on the website, even though they provide nice visuals. E.g. currently they are below the fold inside the documentation (https://www.jaegertracing.io/docs/1.8/). Could we find a place on the home page?

[yurishkuro]

cc @lucperkins @tiffon for ideas

[pavolloffay]

We should add

• trace graph
• compare traces

trace view could be changed with the trace comparison buttons.

[tiffon]

I would suggest not including a ss of the trace graph view while the view is still experimental.