user-dev-guide: add rrepair trivial algorithm sequence diagram
user-dev-guide: add rrepair trivial algorithm sequence diagram

TODO: update the other rrepair sequence diagrams
digshock/scalaris,seyyed/scalaris,digshock/scalaris,tectronics/scalaris,seyyed/scalaris,seyyed/scalaris,tectronics/scalaris,digshock/scalaris,seyyed/scalaris,digshock/scalaris,seyyed/scalaris,digshock/scalaris,digshock/scalaris,digshock/scalaris,tectronics/scalaris,tectronics/scalaris,seyyed/scalaris,tectronics/scalaris,seyyed/scalaris,tectronics/scalaris,tectronics/scalaris