No need to rename the comics.txt
For example if you have already zipped your chapters as one.cbz, two.cbz, three.cbz, 004.cbz you want your comics.txt to look like:
one.cbz:Chapter one
two.cbz:Chapter two
three.cbz:Chapter three
004.cbz:Chapter four
Then you zip all four CBZs plus the comics.txt together, then rename it as cbc.
the reason why you would want to edit the comics.txt is because it is what Calibre will use as your TOC, so for the comics.txt above, after you transfer the book to your reader, the TOC will read
Chapter one
Chapter two
Chapter three
Chapter four
Now I know I would want that to be something like:
Chapter 001 - Romance Dawn - The Beginning of the Adventures
Chapter 002 - That Boy The Straw Hat Wearing Luffy
Chapter 003 - Pirate Hunter Zoro' Enters
Chapter 004 - Marine Lieutenant 'Axe Arm Morgan'
Chapter 005 - Pirate King and the Great Swordsman
Chapter 006 - First Person
Chapter 007 - Friend
Chapter 008 - Nami Enters
