doc: shortlog: put back trailer paragraphs

47beb37 (shortlog: match commit trailers with --group, 2020-09-27)
added the `trailer` bullet point with three paragraphs.[1] Later,
3dc95e0 (shortlog: support arbitrary commit format `--group`s,
2022-10-24) put the single-paragraph bullet point about `format` right
after the first paragraph about `trailer`. That meant that the second
and third paragraphs for `trailer` got moved to `format`.

Move the two paragraphs back to `trailer`. We now also need one blank
line before the final bullet point so that it does not get joined with
the second bullet point.

† 1: Technically the bullet list formatting was immediately fixed to
     include all three paragraphs in 63d24fa (shortlog: allow multiple
     groups to be specified, 2020-09-27)

Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: LemmingAvalanche

Documentation/git-shortlog.adoc

@@ -64,9 +64,6 @@ OPTIONS
    example, if your project uses `Reviewed-by` trailers, you might want
    to see who has been reviewing with
    `git shortlog -ns --group=trailer:reviewed-by`.
- - `format:<format>`, any string accepted by the `--format` option of
-   'git log'. (See the "PRETTY FORMATS" section of
-   linkgit:git-log[1].)
 +
 Note that commits that do not include the trailer will not be counted.
 Likewise, commits with multiple trailers (e.g., multiple signoffs) may
@@ -77,6 +74,10 @@ Shortlog will attempt to parse each trailer value as a `name <email>`
 identity. If successful, the mailmap is applied and the email is omitted
 unless the `--email` option is specified. If the value cannot be parsed
 as an identity, it will be taken literally and completely.
+
+ - `format:<format>`, any string accepted by the `--format` option of
+   'git log'. (See the "PRETTY FORMATS" section of
+   linkgit:git-log[1].)
 --
 +
 If `--group` is specified multiple times, commits are counted under each