doc: fix asciidoc format compatibility in pretty-formats.adoc
Asciidoc.py and Asciidoctor do not process the '+' verbatim the same way. A span is detected when the format sign (here '+')is preceded by a non-word character. It seems that '{nbsp}' is considered a non-word sign by Asciidoc.py, but not by Asciidoctor. Using a double format-sign opens 'unconstrained' span, independent on the preceding character in both engines. The '+' sign is used instead of the backtick '`' because it is not processed as synopsis in asciidoc.py. Unfortunately, the post-processing of verbatim synopsis in asciidoctor cannot be bypassed and formatting of the parentheses is forced in syntax sign instead of keywords, unless a proper grammar analyzer is used. Signed-off-by: Jean-Noël Avila <jn.avila@free.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>