[Cin]Adjacent edits in timeline

Based on Georgy's email ( https://www.mail-archive.com/cin@lists.cinelerra-gg.org/msg09216.html) and his further explanations, I would like to propose an addition to the manual regarding an important aspect of CinGG's operation. I am attaching a document and link to an image (https://i.postimg.cc/KjD1SXZS/AV-sync.png). If you can improve, correct, and add information, we can then consider modifying the manual.