Here is a list of all documented files with brief descriptions:

apiattr.h
assert.h
auth.h
cntl-private.h
cntl.h	Command codes for libcouchbase
couchbase.h
crypto.h
environment.h
error.h	Definition of all of the error codes used by libcouchbase
intro.h
iops.h	Public I/O integration interface
ixmgmt.h
kvbuf.h
libev_io_opts.h
libevent_io_opts.h
libuv_io_opts.h
logger.h
mainpage.h
metrics.h
pktfwd.h
sysdefs.h
tracing.h
utils.h
vbucket.h	VBucket Mapping API
visibility.h
wsaerr.h