blame-options.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>" and "-L :<regex>", 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>

Documentation/blame-options.txt

@@ -9,7 +9,8 @@
 --show-stats::
 	Include additional statistics at the end of blame output.
 
--L <start>,<end>, -L :<regex>::
+-L <start>,<end>::
+-L :<regex>::
 	Annotate only the given line range.  <start> and <end> can take
 	one of these forms: