Add screenshot of the program to the begin of README

[NeizKap]

I get used to look at screenshot firstly to estimate an appearance of any program before downloading

[BLumia]

The deepin apps are mostly preinstalled when using DDE or the deepin distribution, which you unlikely will need a screenshot. IMO adding AppStream metadata and provide the screenshots metadata could be more helpful for regular users, so they can preview the app while using an app-store thingy.

Just for curiosity, which repo is the one that lead you here?