2.5.+ edits to 'change user password'

Signed-off-by: Sam Kleinman <samk@10gen.com>
edits to change user password tutorial
removing example box
DOCS-2237: style clean up for user management commands
change to ref-toc description for updateUser

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-2161 new create user syntax

Signed-off-by: Sam Kleinman <samk@10gen.com>
minor wording change
add toc refs for change-user-privileges
DOCS-2249 redirect for change-user-privileges tutorial