Besides the built-in man pages, we could also have http://wp-cli.org/manual/.

wp help --web blog create would open a browser to http://wp-cli.org/manual/blog-create.html

http://wp-cli.org/manual/ would also have an index page with all the available commands, which would replace the manually updated wiki pages:

• https://github.com/wp-cli/wp-cli/wiki/List-of-internal-commands
• https://github.com/wp-cli/wp-cli/wiki/List-of-community-commands

Related: #24