Here is an overview of the docs in the doc/features directory.

account-notify.txt	- Description of the account-notify system
away-notify.txt		- Description of the away-notify system
challenge.txt		- Overview of the challenge/response system for
                          obtaining operator status
collision_fnc.txt	- Overview of the SAVE nick collision method
extban.txt		- Description of extended bans
extended-join.txt	- Description of the extended-join system
modeg.txt		- Description of UMODE +g, the caller ID system
monitor.txt		- Description of the MONITOR system
sasl.txt		- Description of the SASL services authentication
			  system
services.txt		- Overview of features added by services
tgchange.txt		- Overview of the target change system
