You can see the Coot User Manual (PostScript) (pdf), which gives a good idea of the features of Coot. It is also in A5 duplex format - for the saving of trees (and the straining of eyes possibly).
There is a PostScript tutorial.
HTML versions:
Also available is A Quick Guide to Coot's Keys and Buttons, print it out and stick it on your wall.
Documentation on the scripting interface. This displays the fuction names from the point of view of a python scripter (scheme scripters will have to do a trivial name mapping (described therein)).
Documentation for the Coot functions written in scheme.
Documentation for the Coot functions written in python.
And for the hard-core Coot scripters, there's The Coot Reference Manual (note: this is autogenerated and doesn't make for light reading).