Design document for segment merge process

[Seunghyun Lee]

Hi all,

I have written the design document for the segment merge. Please review the
document and any kind of feedback is welcome :)


https://docs.google.com/document/d/1-AKCfXNXdoNjFIvJ87wjWwFM_38gS0NCwFrIYjYsqp8/edit?usp=sharing

Best,
Seunghyun