Here you can find the help files that come with the game (accessed using '?'), but in swish online format. This help is up-to-date for Angband 3.4.1.
If you're looking for strategy and tactics for playing the game, have a look at the Players' Guide for lots of hints and tips.
There's a user manual that comes with the game, which is more focussed on describing the game in exhaustive detail. Enjoy!