for-each-ref: fix documentation argument ordering

Improve the 'git-for-each-ref(1)' documentation with two corrections:

1. Add parentheses around `--exclude=<pattern>` to indicate this option
   can be repeated as a complete unit.

2. Move `--stdin | <pattern> ...` to the end, after all flags, since
   `<pattern>` is a positional argument that should appear last in the
   argument list.

While here, change to using the synopsis block which will automatically
format placeholders in italics and keywords in monospace.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: KarthikNayak

Documentation/git-for-each-ref.adoc

@@ -7,14 +7,14 @@ git-for-each-ref - Output information on each ref
 
 SYNOPSIS
 --------
-[verse]
-'git for-each-ref' [--count=<count>] [--shell|--perl|--python|--tcl]
+[synopsis]
+git for-each-ref [--count=<count>] [--shell|--perl|--python|--tcl]
 		   [(--sort=<key>)...] [--format=<format>]
-		   [--include-root-refs] [ --stdin | <pattern>... ]
-		   [--points-at=<object>]
+		   [--include-root-refs] [--points-at=<object>]
 		   [--merged[=<object>]] [--no-merged[=<object>]]
 		   [--contains[=<object>]] [--no-contains[=<object>]]
-		   [--exclude=<pattern> ...] [--start-after=<marker>]
+		   [(--exclude=<pattern>)...] [--start-after=<marker>]
+		   [ --stdin | <pattern>... ]
 
 DESCRIPTION
 -----------