The main source of "knowledge" about dfhack is not any readme, and will never be a readme. It can only tell you about the fixed part of dfhack i.e. the part we wrote, the part that has the infrastructure, the usage details of plugins etc... We can't (or at least i won't) write a guide/readme about the part thats from DF. The part that holds e.g. entity membership. The main reasons are: it will probably change with next df version, there is a ton of it, nobody (except Toady One) knows what does what exactly. Other than that the fastest way is either to dig through
df-structures , join our irc channel and ask around, try using gui/gm-editor to get the feel for structures and inner working of df, analyze the other plugins and scripts. The best example is creature creation script. It was not made for so long because nobody knew how it works and some fields were unknown. After some playing around (and df crashing) we have a working creature spawning script. Though it still is missing a lot of details and customization (e.g. memberships, history, starting afflictions, event birth date(age), inventory, maybe appearance customization, beliefs and family relations and so on) my idea was to spawn a creature and then modify it to your liking.