Use the phrase "configuration variables" instead of "rules" because
(1) we already say "configuration variables" in multiple
places in the docs (where the word "rules" is only used for describing
"--only-input" behavior and for an unrelated case of mentioning how
the trailers do not follow "rules for RFC 822 headers"), and
(2) this phrase is more specific than just "rules".
Signed-off-by: Linus Arver <linusa@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>