docs/pretty-formats: stress that %- removes all preceding line-feeds

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/pretty-formats.txt

@@ -213,8 +213,8 @@ If you add a `+` (plus sign) after '%' of a placeholder, a line-feed
 is inserted immediately before the expansion if and only if the
 placeholder expands to a non-empty string.
 
-If you add a `-` (minus sign) after '%' of a placeholder, line-feeds that
-immediately precede the expansion are deleted if and only if the
+If you add a `-` (minus sign) after '%' of a placeholder, all consecutive
+line-feeds immediately preceding the expansion are deleted if and only if the
 placeholder expands to an empty string.
 
 If you add a ` ` (space) after '%' of a placeholder, a space