FIXes location of -- for grep

Broken in 5b1ac3c

`--` must be after all parameters (options), and before positional arguments

See https://unix.stackexchange.com/questions/11376/what-does-double-dash-mean-also-known-as-bare-double-dash

bin/git-contrib

@@ -6,4 +6,4 @@ test -z "$user" && echo "user name required." 1>&2 && exit 1
 
 count=`git log --oneline --pretty="format: %an" | grep -- "$user" | wc -l`
 test $count -eq 0 && echo "$user did not contribute." && exit 1
-git shortlog | grep -- "$user (" -A $count
+git shortlog | grep -A $count -- "$user ("