doc: git bisect: clarify the usage of the synopsis vs actual command

doc: git bisect: clarify the usage of the synopsis vs actual command

The difference between a synopsis and an actual command is that the synopsis
is a more abstract representation of the command, which may include
placeholders for arguments and options. The actual command is the specific
instance of the command with all the arguments and options filled in.

The formatting of an actual command is a code block, with the command
prefixed by a dollar sign ($) to indicate that it is a command to be run in
the terminal. It can also include comments with a hash sign (#) to explain
the command or provide additional information, just like in a regular
terminal session.

Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>