git-sparse-checkout.txt: shuffle some sections and mark as internal
With cone mode as the default, it makes sense to discuss it before
non-cone mode. Also, the new default means we can just use directories
in most cases and users do not need to understand patterns or their
meanings. Let's take advantage of this to mark several sections as
"INTERNALS", notifying the user that they do not need to know all those
details in order to make use of the sparse-checkout command.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>