format-patch documentation: Remove diff options that are not useful

format-patch documentation: Remove diff options that are not useful

To simplify reading the documentation for format-patch, remove the
description of common diff options that are not useful for the
purpose of the command (i.e. "Prepare patches for e-mail submission").

Specifically, this removes the description of the following options:

  --raw
  -z
  --color
  --no-color
  --color-words
  --diff-filter
  -S
  --pickaxe-all
  --pickaxe-regex
  -R
  --relative
  --exit-code
  --quiet

Signed-off-by: Björn Gustavsson <bgustavsson@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>