bookmarks: update help text since moving into core
Clarifies the help text for the bookmarks command regarding the
requirements for pushing or pulling bookmarks.
$ mkdir t
$ cd t
$ hg init
$ echo a > a
$ hg add a
$ hg commit -m test
$ rm .hg/requires
$ hg tip
abort: index 00changelog.i unknown format 2!
[255]
$ echo indoor-pool > .hg/requires
$ hg tip
abort: requirement 'indoor-pool' not supported!
[255]