git config doc: fix recent ASCIIDOC formatting regression

git config doc: fix recent ASCIIDOC formatting regression

Fix a regression in 8c328561332 (blame: document --color-* options,
2021-10-08), which added an extra newline before the "+" syntax.

The "Documentation/doc-diff HEAD~ HEAD" output with this applied is:

    [...]
    @@ -1815,13 +1815,13 @@ CONFIGURATION FILE
                specified colors if the line was introduced before the given
                timestamp, overwriting older timestamped colors.

    -       + Instead of an absolute timestamp relative timestamps work as well,
    -       e.g. 2.weeks.ago is valid to address anything older than 2 weeks.
    +           Instead of an absolute timestamp relative timestamps work as well,
    +           e.g.  2.weeks.ago is valid to address anything older than 2 weeks.

    -       + It defaults to blue,12 month ago,white,1 month ago,red, which colors
    -       everything older than one year blue, recent changes between one month
    -       and one year old are kept white, and lines introduced within the last
    -       month are colored red.
    +           It defaults to blue,12 month ago,white,1 month ago,red, which
    +           colors everything older than one year blue, recent changes between
    +           one month and one year old are kept white, and lines introduced
    +           within the last month are colored red.

            color.blame.repeatedLines
                Use the specified color to colorize line annotations for git blame

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>