rationale for writting libpasspgrase

Signed-off-by: Mattias Andrée <maandree@operamail.com>
add reationale for writting cerberus

Signed-off-by: Mattias Andrée <maandree@operamail.com>
add rationale for writting gates-of-tartaros

Signed-off-by: Mattias Andrée <maandree@operamail.com>