Documentation/git-for-each-ref: clarify peeling of tags for --format

Documentation/git-for-each-ref: clarify peeling of tags for --format

`*` in format strings means peeling of tag objects so that object field
names refer to the object that the tag object points at, instead of the
tag object itself.

Currently, this is documented using grammar that is clearly inspired by
classical latin, though missing more than an article in order to be
classical english.

Try and straighten that explanation out a bit.

Signed-off-by: Michael J Gruber <git@grubix.eu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>