git-log.txt: place each -L option variation on its own line

Standard practice in Git documentation is for each variation of an option (such as: -p / --porcelain) to be placed on its own line in the OPTIONS table. The -L option does not follow suit. It cuddles "-L <start>,<end>:<file>" and "-L :<regex>:<file>", separated by a comma. This is inconsistent and potentially confusing since the comma separating them is typeset the same as the comma in "<start>,<end>". Fix this by placing each variation on its own line. Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>